[Feature] Return to folder view scrolls to and highlights the last viewed asset

[lalakiop]

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request.

• Yes

The feature

Summary
When browsing assets in the Folders view, tapping a photo opens the full-screen asset viewer. After swiping through several photos and then going back, the folder list stays at the position where the user originally entered (the asset that was tapped), not where they stopped browsing. It would be nice if the list automatically scrolled to the last viewed asset and highlighted it on return.

Proposed behavior

• After returning from the asset viewer, the folder list scrolls to the last viewed asset.
• The asset tile is visually highlighted (e.g. tinted background) so the user can continue from where they left off.

Technical notes (from code)

• assetViewerProvider is a global provider and is not reset when the viewer closes, so the last viewed currentAsset is still readable after pop (mobile/lib/providers/asset_viewer/asset_viewer.provider.dart).
• The folder page (mobile/lib/pages/library/folder/folder.page.dart) currently opens the viewer with unawaited(context.pushRoute(AssetViewerRoute(...))) and its ListView has no ScrollController, so no scroll-back logic exists.
• On return the asset can be matched via BaseAsset.refersToSameAsset().
• LargeLeadingTile already supports selected / selectedTileColor, which can be reused for the highlight.
• Scope: changes are confined to the folder page; no viewer changes required.

Platform

• Server
• Web
• Mobile