Live agent todo list: compact scrollable strip above the composer

Add a todo.update frame (server->app) carrying the agent's full current
todo list. The gateway emits it whenever the hermes todo tool completes
(the tool result is authoritative even for merge writes) and re-sends a
snapshot right after hello so a reconnecting device re-learns the plan.
Ephemeral: never outboxed.

The app renders it as a compact strip above the composer (max 3 lines,
the rest scrollable) mirroring the hermes desktop composer status stack:
pending = hollow ring, in_progress = spinner, completed = green check,
cancelled = struck through. It auto-scrolls to the current task whenever
the active task changes, and hides itself once the list is empty or fully
resolved.

gateway-plugin/http_server.py

@@ -223,9 +223,7 @@ class HttpServer:
             return
 
         self._httpd = httpd
-        self._thread = threading.Thread(
-            target=httpd.serve_forever, name="iris-http", daemon=True
-        )
+        self._thread = threading.Thread(target=httpd.serve_forever, name="iris-http", daemon=True)
         self._thread.start()
         self.enabled = True
         scheme = "https" if (self._adapter.http_cert and self._adapter.http_key) else "http"
@@ -513,6 +511,10 @@ class HttpServer:
             self._write_sse(
                 handler, "frame", None, protocol.status(self._adapter.gateway_status()).to_json()
             )
+            # 2b. Live todo-list snapshot (ephemeral state, never outboxed):
+            # a (re)connecting device re-learns the agent's current plan here.
+            for snap in self._adapter.todo_snapshot_frames():
+                self._write_sse(handler, "frame", None, snap.to_json())
             # 3. Live frames (cursor=None frames have no id).
             while not sub.closed.is_set():
                 try: