M5: push (FCM + ntfy) + offline catch-up + background notifications

Server (gateway-plugin):
- push.py: FCM (HTTP v1 service-account / legacy key) + ntfy backends; NtfyBackend.server_url for app discovery
- adapter.py: push on offline broadcast + high-priority push when live; fcm.register; server_caps.push_ntfy_server; outbox now ALWAYS appends so a reconnecting app catches up on live-delivered frames (fixes empty chat after notification tap / activity recreation)
- protocol.py / ws_server.py / outbox.py / plugin.yaml: M5 frames + env vars

App (Kotlin CMP):
- Protocol.kt: notification / fcm.register / sync frames + push caps
- GatewayClient.kt: hello carries push creds; auto-sync on reconnect
- IrisController.kt: banners, deep-link, notifyMessageIfBackgrounded (system notification on a regular reply when backgrounded)
- Android: PlatformPush, AppBridge, IrisNotifications, NtfyListenerService, IrisFirebaseMessagingService, AndroidPush, AndroidSecureStore
- Desktop: DesktopPush, DesktopSecureStore
- build files + manifest (permissions, services, deep-links)

Tests: 35-test tests/gateway/test_android.py suite passes (incl. new regression test_live_delivered_frame_still_parked_for_sync). E2E verified on device: push fire, reconnect sync, background notification, and message replay after ChatStore reset.

gateway-plugin/ws_server.py

@@ -316,18 +316,8 @@ class WsServer:
             await self._adapter.on_media_upload_end(frame, device_id)
         elif frame.type == protocol.TYPE_MEDIA_PULL:
             await self._adapter.on_media_pull(frame, device_id)
-        elif frame.type == "fcm.register":
-            fcm_token = frame.payload.get("fcm_token")
-            ntfy_topic = frame.payload.get("ntfy_topic")
-            if isinstance(fcm_token, str) or isinstance(ntfy_topic, str):
-                try:
-                    self._devices.update_push_tokens(
-                        device_id,
-                        fcm_token=fcm_token if isinstance(fcm_token, str) else None,
-                        ntfy_topic=ntfy_topic if isinstance(ntfy_topic, str) else None,
-                    )
-                except Exception:
-                    logger.warning("android: fcm.register update failed", exc_info=True)
+        elif frame.type == protocol.TYPE_FCM_REGISTER:
+            await self._adapter.on_fcm_register(frame, device_id)
         # Unknown types are ignored (forward-compat).
 
     # ── Helpers ───────────────────────────────────────────────────────────