feat(locallibrary): complete Albums 1:1 + dedicated local album view with versions

Albums tab — full 1:1 with Tauri in one pass:
- Switch from the chunked-paginated grid to a full-load + in-memory derive so
  grouping/filtering span the whole set. derive_albums = search + sort + group
  (off / by letter with A-Z jump / by artist, both with section headers) + the
  quality/format/source filter (1:1 with matchesQualityFilters: OR within a
  group, AND between groups; empty group passes).
- Grid/list view toggle; the list view shows a SOURCE column (Local/Offline/
  Plex), placed after TYPE. Filter popup now FLOATS (sibling of the content
  layout, not a layout slot) with an active-count badge. Fixed the year sort
  (sort_album_items maps year-asc/desc — was also silently broken in Folders).
- Album covers dual-set by id across the full set + visible + grouped sections.

Dedicated local album view — SEPARATE from the Qobuz AlbumView:
- New ContentView::local-album + NavEntry::LocalAlbum + ui/album/LocalAlbumView.slint,
  reusing TrackRow/NavButtons/CircleAction/QualityBadge internals but ONLY local
  actions (play all / shuffle / edit tags / add to playlist) — no Qobuz chrome.
- Versions: an album's tracks are split by source directory into versions, so
  multiple copies of the same album no longer merge into a duplicated track
  list. Best-quality version is the default; a source-icon version picker
  (hard-drive / Qobuz / Plex glyph in both the selected display and the options)
  switches the shown copy in place. The album cover is the best-quality version
  that has one, falling through versions, else a placeholder (covers backfilled
  from disk via fill_missing_covers). Header padding-top 11px matches the app.

Fix: Artists tab deadlock — fetch_missing_artist_images snapshotted names with a
blocking rx.recv() called from inside an event-loop closure, freezing the UI
(static spinner, no error). Names are now snapshotted on the UI thread and
passed in; the worker never blocks the event loop.

cc

crates/qbz-slint/ui/primitives/AlbumListRow.slint

@@ -269,11 +269,11 @@ export component AlbumListRow inherits Rectangle {
         // --- SOURCE (hideable) ----------------------------------------
         if root.show-source: Text {
             width: AlbumListCols.source;
-            text: root.album.source == "qobuz"
-                ? @tr("Qobuz")
-                : (root.album.source == "plex"
-                    ? @tr("Plex")
-                    : (root.album.source == "local" ? @tr("Local") : ""));
+            text: root.album.source == "qobuz" ? @tr("Qobuz")
+                : root.album.source == "qobuz_download" ? @tr("Offline")
+                : root.album.source == "plex" ? @tr("Plex")
+                : root.album.source == "local" ? @tr("Local")
+                : "";
             color: Theme.text-secondary;
             font-size: 12px;
             vertical-alignment: center;