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/mesh/listener/dispatch.rs

@@ -697,6 +697,10 @@ async fn dispatch_block_header(
     sender_name: &str,
     state: &Arc<MeshState>,
 ) {
+    // Respect the receive toggle (issue #28): nodes can opt out of inbound headers.
+    if !state.receive_block_headers {
+        return;
+    }
     // Compact binary format: height(8) + hash(32) + timestamp(4)
     match super::super::bitcoin_relay::decode_compact_block_header(&envelope.v) {
         Ok((height, hash_hex, timestamp)) => {

core/archipelago/src/mesh/listener/mod.rs

@@ -102,6 +102,8 @@ pub struct MeshState {
     pub session_manager: Arc<super::session::SessionManager>,
     /// Whether to encrypt directed relay messages (config toggle for rollback).
     pub encrypt_relay: bool,
+    /// Whether to accept inbound Bitcoin block headers from peers (issue #28).
+    pub receive_block_headers: bool,
     /// Last-seen presence heartbeats per peer pubkey hex: (status, last_active_epoch, received_at).
     pub presence: RwLock<HashMap<String, (String, u32, u64)>>,
     /// Contacts store — alias/notes/pinned/blocked per peer pubkey hex.
@@ -151,6 +153,7 @@ impl MeshState {
         relay_tracker: Option<Arc<super::bitcoin_relay::RelayTracker>>,
         stego_mode: super::steganography::SteganographyMode,
         encrypt_relay: bool,
+        receive_block_headers: bool,
         session_manager: Arc<super::session::SessionManager>,
         our_ed_pubkey_hex: String,
     ) -> (
@@ -187,6 +190,7 @@ impl MeshState {
             chunk_buffer: RwLock::new(HashMap::new()),
             session_manager,
             encrypt_relay,
+            receive_block_headers,
             presence: RwLock::new(HashMap::new()),
             contacts: RwLock::new(HashMap::new()),
             our_ed_pubkey_hex,

core/archipelago/src/mesh/mod.rs

@@ -169,6 +169,10 @@ pub struct MeshConfig {
     /// Announce new Bitcoin block headers over mesh (internet-connected nodes only).
     #[serde(default)]
     pub announce_block_headers: bool,
+    /// Accept Bitcoin block headers received over mesh from peers. On by default;
+    /// turn off to ignore inbound headers (the receive half of issue #28).
+    #[serde(default = "default_true")]
+    pub receive_block_headers: bool,
     /// Steganographic encoding mode for mesh messages (Normal = disabled).
     #[serde(default)]
     pub steganography_mode: steganography::SteganographyMode,
@@ -192,6 +196,7 @@ impl Default for MeshConfig {
             advert_name: None,
             mesh_only_mode: None,
             announce_block_headers: false,
+            receive_block_headers: true,
             steganography_mode: steganography::SteganographyMode::Normal,
             encrypt_relay_messages: true,
         }
@@ -360,6 +365,7 @@ impl MeshService {
             Some(Arc::clone(&relay_tracker)),
             config.steganography_mode,
             config.encrypt_relay_messages,
+            config.receive_block_headers,
             Arc::clone(&session_manager),
             ed_pubkey_hex.to_string(),
         );