feat(wallet): LND wedge watchdog + Fedi send rail + token QRs + Auto hidden

- LND watchdog: framework-pt's LND sat wedged 14h (RPC up, server never
  ready, channels inactive) with nothing noticing. 15 consecutive bad
  minutes now bounce the container automatically (30min cooldown) —
  silent multi-hour Lightning outages become self-healed blips.
- Send modal: Auto tab hidden; Ecash splits into Cashu and Fedi (new
  wallet.fedimint-send RPC wrapping the existing spend_from_any); both
  rails render the generated token as a scannable QR alongside the
  copyable text.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/api/rpc/fedimint.rs

@@ -118,6 +118,31 @@ impl RpcHandler {
         Ok(serde_json::json!({ "removed": removed }))
     }
 
+    /// `wallet.fedimint-send` — spend ecash notes from any joined federation
+    /// with sufficient balance. Returns the notes token for the recipient
+    /// (rendered as text + QR by the send modal — the wallet's Fedi rail,
+    /// split from Cashu 2026-07-22). The heavy lifting already existed in
+    /// `fedimint_client::spend_from_any`; it was simply never exposed.
+    pub(super) async fn handle_wallet_fedimint_send(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let amount_sats = params
+            .as_ref()
+            .and_then(|p| p.get("amount_sats"))
+            .and_then(|v| v.as_u64())
+            .ok_or_else(|| anyhow::anyhow!("Missing amount_sats"))?;
+        anyhow::ensure!(amount_sats > 0, "must be at least 1 sat");
+        let (token, federation_id) =
+            crate::wallet::fedimint_client::spend_from_any(&self.config.data_dir, amount_sats)
+                .await?;
+        Ok(serde_json::json!({
+            "token": token,
+            "federation_id": federation_id,
+            "amount_sats": amount_sats,
+        }))
+    }
+
     /// `wallet.fedimint-balance` — total sats across all joined federations.
     pub(super) async fn handle_wallet_fedimint_balance(&self) -> Result<serde_json::Value> {
         // Soft-fail to zero when clientd isn't installed/running, so the unified