fix(mobile): force AssetViewerPage recreation on repeated view intents (#29235)

* fix(mobile): force AssetViewerPage recreation on repeated view intents

When View in Immich is triggered a second time while the viewer is
already open, auto_route's replaceAll reuses the existing route (same
type, null key) and Flutter keeps the old ConsumerState alive. The
PageController and preloader inside _AssetViewerState are late final,
so they never reset — the viewer stays frozen on the previous asset.

Passing UniqueKey() to AssetViewerRoute ensures each view intent
creates a fresh widget element, so initState runs, the PageController
is initialised from scratch, and the new TimelineService from the
updated ProviderScope override is picked up correctly.

Fixes #29230

* clean up

---------

Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

mobile/lib/providers/view_intent/view_intent_handler_android.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 import 'package:immich_mobile/domain/services/timeline.service.dart';
@@ -97,7 +98,7 @@ class AndroidViewIntentHandler implements ViewIntentHandler {
 
     await _router.replaceAll([
       const TabShellRoute(),
-      AssetViewerRoute(initialIndex: 0, timelineService: timelineService),
+      AssetViewerRoute(key: UniqueKey(), initialIndex: 0, timelineService: timelineService),
     ]);
   }
 }