fix: show Properties for Recycle Bin and Favorites folders

[MiMoHo]

Type of change(s)

• Bug fix

What changed and why

Long-pressing the Recycle Bin or Favorites folder and tapping the Properties (i) icon did nothing. DirectoryAdapter.showProperties() opened the single-path PropertiesDialog only inside an if (path != FAVORITES && path != RECYCLE_BIN) guard with no else branch, so both virtual folders fell through and the action was a silent no-op. The guard existed because these folders have virtual DB paths ("recycle_bin" / "favorites") that are not real files, and the single-path PropertiesDialog rejects non-existent paths.

The fix gathers the real underlying media paths and shows them in the multi-path PropertiesDialog:

• Recycle Bin: getUpdatedDeletedMedia() (rewrites the virtual prefix to the actual recycleBinPath location).
• Favorites: getFavoritePaths() (FavoritesDao.getValidFavoritePaths()).

Both helpers run Room queries and GalleryDatabase is built without allowMainThreadQueries(), so they must run off the UI thread — otherwise Room throws and the helpers silently return empty lists. They are therefore executed on a background thread via ensureBackgroundThread, then the dialog is shown back on the UI thread. An isNotEmpty() guard avoids passing an empty list to the multi-path constructor (which indexes fileDirItems[0]).

Tests performed

Built the fossDebug variant and verified on an Android 15 (API 35) emulator:

Created a Favorite and a recycle-bin item; on folders screen long-pressed 'Recycle bin' -> Properties opened a dialog (Items selected 1 / Size 1.4 MB / Files 1). Repeated for 'Favorites' -> Properties dialog opened. Previously nothing happened.

Also confirmed detekt, lint, unit tests and the build all pass locally (CI-equivalent).

Closes the following issue(s)

• Closes Propteries doesn't work on Recycle bin & favorites folder #976

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator.
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• I understand every change in this pull request.

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_{Coded with Opus 4.8 ultracode.}