feat(cms): add Track Browser foundation with mode toggle and CmsTrackGrid

- Extend ICmsTrackService.GetPagedAsync with album/genre filter params
- Add CmsTrackBrowserViewModel (DI-scoped) with lazy album/genre load
- Extract CmsTrackGrid: 9-column layout, waveform status, per-row generate,
  info tooltip, album/genre filter params, OnStatusLoaded callback
- Restructure TrackList: remove MudTabs, add three @page routes, mode toggle,
  Generate All Missing button; album/genre stubs for next wave

DeepDrftManager/Services/ICmsTrackService.cs

@@ -41,10 +41,13 @@ public interface ICmsTrackService
     Task<Result> DeleteTrackAsync(long id, CancellationToken ct = default);
 
     /// <summary>
-    /// Fetch a page of track metadata from the Content API's <c>GET api/track/page</c>.
+    /// Fetch a page of track metadata from the Content API's <c>GET api/track/page</c>. Optional
+    /// <paramref name="album"/> and <paramref name="genre"/> filters narrow the result to a single
+    /// release title or genre; null leaves the dimension unfiltered.
     /// </summary>
     Task<ResultContainer<PagedResult<TrackDto>>> GetPagedAsync(
         int page, int pageSize, string? sortColumn, bool sortDescending,
+        string? album = null, string? genre = null,
         CancellationToken ct = default);
 
     /// <summary>