feat(upload): persistent "Recently uploaded" list (§A8)

The transient client-side upload queue vanished on refresh, so a just-
uploaded track seemed to disappear. Add a server-backed "Recently
uploaded" section (source=upload, newest first) that survives refresh and
auto-refreshes after each upload (the upload mutation already invalidates
the `Track` tag this query provides).

- api: `source` filter on `LibraryFilters` → `GET /tracks?source=`
- i18n: `upload.recent.*` (en + ru); loading/error/empty states

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/api/endpoints/library.ts

@@ -42,6 +42,7 @@ function trackParams(f: LibraryFilters) {
     q: f.search,
     artist_id: f.artistId,
     album_id: f.albumId,
+    source: f.source,
     sort_by: f.sortBy ? SORT_BY[f.sortBy] : undefined,
     order: f.sortOrder,
     ...paging(f.page, f.pageSize),