fix(mesh): native E2E DM for archy↔archy text + software radio-reboot

- send_message now sends archy↔archy plain text as a native TEXT_MESSAGE_APP
  DM (firmware PKC-encrypts E2E), not wrapped in the binary typed envelope
  that silently broke archy↔archy LoRa delivery. Archy peers' Sent rows are
  marked encrypted so the E2E pill shows; rich typed msgs still use the
  typed-wire path.
- Add a software radio-reboot to recover a wedged/RX-deaf radio without
  physical access (and for the Device-tab settings panel): driver reboot()
  via AdminMessage reboot_seconds=97 (verified vs meshtastic/protobufs),
  MeshCommand::RebootRadio, MeshService::reboot_radio, RPC mesh.reboot-radio.
- Handoff doc: docs/SESSION-1.8.0-OTA-PROGRESS.md "RESUME HERE" — RF link is
  the proven blocker (radios not hearing each other); modem_preset mismatch
  is the prime suspect; on-device Meshtastic-app check + fix plan documented.

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

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

@@ -366,6 +366,7 @@ impl RpcHandler {
             "mesh.send" => self.handle_mesh_send(params).await,
             "mesh.send-channel" => self.handle_mesh_send_channel(params).await,
             "mesh.broadcast" => self.handle_mesh_broadcast().await,
+            "mesh.reboot-radio" => self.handle_mesh_reboot_radio(params).await,
             "mesh.configure" => self.handle_mesh_configure(params).await,
             "mesh.send-invoice" => self.handle_mesh_send_invoice(params).await,
             "mesh.send-coordinate" => self.handle_mesh_send_coordinate(params).await,

core/archipelago/src/api/rpc/mesh/messaging.rs

@@ -86,6 +86,29 @@ impl RpcHandler {
         Ok(serde_json::json!({ "broadcast": true }))
     }
 
+    /// mesh.reboot-radio — Reboot the locally-connected radio firmware to
+    /// recover a wedged / RX-deaf radio. Optional `seconds` delay (default 2).
+    pub(in crate::api::rpc) async fn handle_mesh_reboot_radio(
+        &self,
+        params: Option<serde_json::Value>,
+    ) -> Result<serde_json::Value> {
+        let seconds = params
+            .as_ref()
+            .and_then(|p| p.get("seconds"))
+            .and_then(|v| v.as_i64())
+            .unwrap_or(2);
+
+        let service = self.mesh_service.read().await;
+        let svc = service
+            .as_ref()
+            .ok_or_else(|| anyhow::anyhow!("Mesh service not running. Enable mesh first."))?;
+
+        svc.reboot_radio(seconds).await?;
+        info!(seconds, "Mesh radio reboot requested via RPC");
+
+        Ok(serde_json::json!({ "reboot": true, "seconds": seconds }))
+    }
+
     /// mesh.configure — Enable/disable mesh and set device path.
     pub(in crate::api::rpc) async fn handle_mesh_configure(
         &self,