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