fix(pine): node-status mesh_message is {} instead of null when empty

HA's seeded REST sensor reads attributes via json_attributes_path
"$.mesh_message"; a null there makes HA log a "JSON result was not a
dictionary" warning on every 30s scan.

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

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

@@ -136,7 +136,10 @@ impl RpcHandler {
             "bitcoin": bitcoin,
             "mesh": mesh,
             "lightning": lightning,
-            "mesh_message": mesh_message,
+            // Always an object: HA's REST sensor reads attributes via
+            // json_attributes_path "$.mesh_message", and a null there makes
+            // HA log a "JSON result was not a dictionary" warning every scan.
+            "mesh_message": mesh_message.unwrap_or_else(|| json!({})),
         })
     }
 }