feat(wallet,content,seed): Fedimint dual-ecash, paid content streaming, seed ceremony

- Fedimint ecash alongside Cashu: fedimint-clientd (fmcd) HTTP bridge,
  fedimint_client, fedimint RPC, wallet wiring
- Paid peer content: content invoices + streaming content server + content RPCs
- Seed-phrase ceremony/reveal RPCs and CLI ceremony tool
- LND wallet, mesh status/messaging, app-stack (netbird HTTPS), and
  decoupled-update wiring; Fedimint Client core app in catalog

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/archipelago/src/api/handler/content.rs

@@ -66,6 +66,21 @@ impl ApiHandler {
             .and_then(|v| v.to_str().ok())
             .map(|s| s.to_string());
 
+        // Extract a paid-entitlement gate token from X-Invoice-Hash (Lightning)
+        // or X-Onchain-Address (on-chain) — both authorize the download if this
+        // node issued+settled them, and both resolve against the same shared
+        // entitlement store keyed by the token string (#46).
+        let invoice_hash = headers
+            .get("x-invoice-hash")
+            .and_then(|v| v.to_str().ok())
+            .map(|s| s.to_string())
+            .or_else(|| {
+                headers
+                    .get("x-onchain-address")
+                    .and_then(|v| v.to_str().ok())
+                    .map(|s| s.to_string())
+            });
+
         // Extract federation peer DID from X-Federation-DID header
         let peer_did = headers
             .get("x-federation-did")
@@ -82,6 +97,7 @@ impl ApiHandler {
             &config.data_dir,
             content_id,
             payment_token.as_deref(),
+            invoice_hash.as_deref(),
             peer_did.as_deref(),
             range,
         )
@@ -140,6 +156,261 @@ impl ApiHandler {
         }
     }
 
+    /// Seller side (#46): mint a Lightning invoice for a paid catalog item so a
+    /// buyer can pay from any external wallet. Path: GET /content/{id}/invoice.
+    /// Records a pending entitlement keyed by the invoice's payment hash.
+    pub(super) async fn handle_content_invoice(
+        &self,
+        path: &str,
+    ) -> Result<Response<hyper::Body>> {
+        let content_id = path
+            .strip_prefix("/content/")
+            .and_then(|s| s.strip_suffix("/invoice"))
+            .unwrap_or("");
+        if content_id.is_empty() || !is_valid_app_id(content_id) {
+            return Ok(build_response(
+                StatusCode::BAD_REQUEST,
+                "text/plain",
+                hyper::Body::from("Invalid content ID"),
+            ));
+        }
+
+        let catalog = content_server::load_catalog(&self.config.data_dir)
+            .await
+            .unwrap_or_default();
+        let item = match catalog.items.iter().find(|i| i.id == content_id) {
+            Some(i) => i,
+            None => {
+                return Ok(build_response(
+                    StatusCode::NOT_FOUND,
+                    "text/plain",
+                    hyper::Body::from("Content not found"),
+                ))
+            }
+        };
+        let price_sats = match &item.access {
+            content_server::AccessControl::Paid { price_sats } => *price_sats,
+            _ => {
+                // Not a paid item — no invoice to issue.
+                return Ok(build_response(
+                    StatusCode::BAD_REQUEST,
+                    "application/json",
+                    hyper::Body::from(r#"{"error":"Item is not paid"}"#),
+                ));
+            }
+        };
+
+        let memo = format!("Archipelago peer file {content_id}");
+        match self
+            .rpc_handler
+            .create_invoice(price_sats as i64, &memo)
+            .await
+        {
+            Ok((bolt11, payment_hash)) if !payment_hash.is_empty() => {
+                crate::content_invoice::record_pending(&payment_hash, content_id, price_sats).await;
+                let body = serde_json::json!({
+                    "bolt11": bolt11,
+                    "payment_hash": payment_hash,
+                    "price_sats": price_sats,
+                });
+                Ok(build_response(
+                    StatusCode::OK,
+                    "application/json",
+                    hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+                ))
+            }
+            Ok(_) => Ok(build_response(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "application/json",
+                hyper::Body::from(r#"{"error":"Invoice missing payment hash"}"#),
+            )),
+            Err(e) => {
+                let body = serde_json::json!({
+                    "error": format!("Could not create invoice: {e}")
+                });
+                Ok(build_response(
+                    StatusCode::SERVICE_UNAVAILABLE,
+                    "application/json",
+                    hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+                ))
+            }
+        }
+    }
+
+    /// Seller side (#46): report whether a previously-issued invoice has settled.
+    /// Path: GET /content/{id}/invoice-status/{payment_hash}. On settlement the
+    /// entitlement is marked paid so the buyer can then download the file.
+    pub(super) async fn handle_content_invoice_status(
+        &self,
+        path: &str,
+    ) -> Result<Response<hyper::Body>> {
+        let rest = path.strip_prefix("/content/").unwrap_or("");
+        let (content_id, payment_hash) = match rest.split_once("/invoice-status/") {
+            Some((id, hash)) => (id, hash),
+            None => {
+                return Ok(build_response(
+                    StatusCode::BAD_REQUEST,
+                    "text/plain",
+                    hyper::Body::from("Invalid request"),
+                ))
+            }
+        };
+        if content_id.is_empty() || !is_valid_app_id(content_id) || payment_hash.is_empty() {
+            return Ok(build_response(
+                StatusCode::BAD_REQUEST,
+                "text/plain",
+                hyper::Body::from("Invalid request"),
+            ));
+        }
+
+        // The hash must be one we issued for exactly this content item.
+        match crate::content_invoice::lookup(payment_hash).await {
+            Some((cid, _)) if cid == content_id => {}
+            _ => {
+                return Ok(build_response(
+                    StatusCode::NOT_FOUND,
+                    "application/json",
+                    hyper::Body::from(r#"{"error":"Unknown invoice"}"#),
+                ))
+            }
+        }
+
+        // Already paid? Otherwise ask our LND and persist the result.
+        let mut paid = crate::content_invoice::is_paid_for(payment_hash, content_id).await;
+        if !paid {
+            if let Ok(true) = self.rpc_handler.invoice_is_settled(payment_hash).await {
+                crate::content_invoice::mark_paid(payment_hash).await;
+                paid = true;
+            }
+        }
+
+        let body = serde_json::json!({ "paid": paid });
+        Ok(build_response(
+            StatusCode::OK,
+            "application/json",
+            hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+        ))
+    }
+
+    /// Seller side (#46): issue a fresh on-chain address for a paid catalog item
+    /// so a buyer can pay on-chain. Path: GET /content/{id}/onchain. Records a
+    /// pending entitlement keyed by the address; price doubles as expected amount.
+    pub(super) async fn handle_content_onchain(
+        &self,
+        path: &str,
+    ) -> Result<Response<hyper::Body>> {
+        let content_id = path
+            .strip_prefix("/content/")
+            .and_then(|s| s.strip_suffix("/onchain"))
+            .unwrap_or("");
+        if content_id.is_empty() || !is_valid_app_id(content_id) {
+            return Ok(build_response(
+                StatusCode::BAD_REQUEST,
+                "text/plain",
+                hyper::Body::from("Invalid content ID"),
+            ));
+        }
+        let catalog = content_server::load_catalog(&self.config.data_dir)
+            .await
+            .unwrap_or_default();
+        let price_sats = match catalog.items.iter().find(|i| i.id == content_id) {
+            Some(i) => match &i.access {
+                content_server::AccessControl::Paid { price_sats } => *price_sats,
+                _ => {
+                    return Ok(build_response(
+                        StatusCode::BAD_REQUEST,
+                        "application/json",
+                        hyper::Body::from(r#"{"error":"Item is not paid"}"#),
+                    ))
+                }
+            },
+            None => {
+                return Ok(build_response(
+                    StatusCode::NOT_FOUND,
+                    "text/plain",
+                    hyper::Body::from("Content not found"),
+                ))
+            }
+        };
+
+        match self.rpc_handler.new_onchain_address().await {
+            Ok(address) if !address.is_empty() => {
+                crate::content_invoice::record_pending(&address, content_id, price_sats).await;
+                let body = serde_json::json!({
+                    "address": address,
+                    "amount_sats": price_sats,
+                });
+                Ok(build_response(
+                    StatusCode::OK,
+                    "application/json",
+                    hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+                ))
+            }
+            _ => {
+                let body = serde_json::json!({
+                    "error": "Could not generate an on-chain address (is the wallet ready?)"
+                });
+                Ok(build_response(
+                    StatusCode::SERVICE_UNAVAILABLE,
+                    "application/json",
+                    hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+                ))
+            }
+        }
+    }
+
+    /// Seller side (#46): report whether an on-chain payment to a previously-
+    /// issued address has arrived (>= price, >= 1 conf). Path:
+    /// GET /content/{id}/onchain-status/{address}. Marks the entitlement paid.
+    pub(super) async fn handle_content_onchain_status(
+        &self,
+        path: &str,
+    ) -> Result<Response<hyper::Body>> {
+        let rest = path.strip_prefix("/content/").unwrap_or("");
+        let (content_id, address) = match rest.split_once("/onchain-status/") {
+            Some((id, addr)) => (id, addr),
+            None => {
+                return Ok(build_response(
+                    StatusCode::BAD_REQUEST,
+                    "text/plain",
+                    hyper::Body::from("Invalid request"),
+                ))
+            }
+        };
+        if content_id.is_empty() || !is_valid_app_id(content_id) || address.is_empty() {
+            return Ok(build_response(
+                StatusCode::BAD_REQUEST,
+                "text/plain",
+                hyper::Body::from("Invalid request"),
+            ));
+        }
+        // The address must be one we issued for exactly this content item.
+        let price = match crate::content_invoice::lookup(address).await {
+            Some((cid, price)) if cid == content_id => price,
+            _ => {
+                return Ok(build_response(
+                    StatusCode::NOT_FOUND,
+                    "application/json",
+                    hyper::Body::from(r#"{"error":"Unknown address"}"#),
+                ))
+            }
+        };
+
+        let mut paid = crate::content_invoice::is_paid_for(address, content_id).await;
+        if !paid {
+            if let Ok(true) = self.rpc_handler.onchain_received(address, price).await {
+                crate::content_invoice::mark_paid(address).await;
+                paid = true;
+            }
+        }
+        let body = serde_json::json!({ "paid": paid });
+        Ok(build_response(
+            StatusCode::OK,
+            "application/json",
+            hyper::Body::from(serde_json::to_vec(&body).unwrap_or_default()),
+        ))
+    }
+
     /// Serve a degraded preview of paid content (blurred image or first 2% of video).
     pub(super) async fn handle_content_preview(
         path: &str,
@@ -190,6 +461,14 @@ impl ApiHandler {
                     .body(hyper::Body::from(bytes))
                     .unwrap())
             }
+            Ok(content_server::PreviewResult::PreviewUnavailable) => Ok(Response::builder()
+                .status(StatusCode::UNSUPPORTED_MEDIA_TYPE)
+                .header("Content-Type", "text/plain")
+                .header("X-Content-Preview", "unavailable")
+                .body(hyper::Body::from(
+                    "Preview unavailable for this media (needs re-encoding)",
+                ))
+                .unwrap()),
             Ok(content_server::PreviewResult::NotFound) | Err(_) => Ok(build_response(
                 StatusCode::NOT_FOUND,
                 "text/plain",