run_listener() now loops forever instead of returning on first failure.
Connect errors retry starting at 500ms, doubling up to 16s.
On disconnect the inner loop breaks and the outer loop reconnects
after the current backoff delay, then resets backoff to 500ms.
QUERY_RUNNING is sent again on each reconnect to re-sync session state.
Task 10 -- App WebView lifecycle.
appd_ws module (servo-embed gated):
Background thread connects to the appd WebSocket on startup.
Sends QUERY_RUNNING to receive initial running sessions.
Translates LAUNCH_ACK -> AppdCmd::Launch and APP_STATE stopped
-> AppdCmd::Stop, then wakes the winit event loop via the
shared EventLoopWaker.
embedder changes:
App struct gains app_rx (mpsc receiver), app_webviews
(HashMap<session_id, WebView>), active_session, and a stored
rendering_context used when creating app WebViews later.
create_app_webview(): resolves weft-app://<app_id>/index.html
to a file URL, creates a dedicated UserContentManager with the
weftIpc bridge injected (includes window.weftSessionId), builds
and registers a new WebView.
about_to_wait() drains app_rx: creates WebViews for Launch
commands, removes and clears active_session for Stop commands.
active_webview() returns the active-session WebView when one
exists, falling back to the system-ui WebView. Rendering,
keyboard, and mouse events all route through active_webview().
Resize propagates to both the system WebView and all app WebViews.
run() creates the mpsc channel and spawns the appd listener
before entering the winit event loop.
