feat(library): surface metadata enrichment status, errors and covers

The mapper dropped metadata_status and hardcoded availability, so enrichment
state was invisible and a just-uploaded track never appeared to change. Map
metadata_status/metadata_error/has_cover onto Track; add MetadataStatusBadge
(pending spinner / enriched / failed-with-reason / manual) shown in TrackRow,
and serve token-bearing track covers via getTrackCoverUrl.

UploadPage now polls each uploaded track (stops once enrichment settles) so the
resolved title/artist — or a failure reason — appears live. i18n in en + ru.

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

src/components/track/TrackRow.tsx

@@ -1,11 +1,12 @@
 import { Row } from '@olly/modern-sk';
 import { TrackContextMenu } from './TrackContextMenu';
 import { AvailabilityBadge } from './AvailabilityBadge';
+import { MetadataStatusBadge } from './MetadataStatusBadge';
 import { formatDuration } from '../../lib/format';
 import { useAppDispatch, useAppSelector } from '../../hooks/useAppDispatch';
 import { play } from '../../store/slices/player';
 import type { Track } from '../../api/types';
-import { getCoverUrl } from '../../api/endpoints/streaming';
+import { getCoverUrl, getTrackCoverUrl } from '../../api/endpoints/streaming';
 
 interface Props {
   track: Track;
@@ -27,8 +28,13 @@ export function TrackRow({
   const dispatch = useAppDispatch();
   const currentTrackId = useAppSelector((s) => s.player.currentTrackId);
   const isPlaying = useAppSelector((s) => s.player.isPlaying);
+  const token = useAppSelector((s) => s.auth.accessToken);
   const isActive = currentTrackId === track.id;
-  const artUrl = getCoverUrl(track.albumArtUrl);
+  // Prefer an explicit album art URL; otherwise serve the track's own cover
+  // (needs the token in the query string — `<img>` can't send a header).
+  const artUrl =
+    getCoverUrl(track.albumArtUrl) ??
+    (token ? getTrackCoverUrl(track.id, token, track.hasCover) : undefined);
 
   return (
     <Row
@@ -95,7 +101,13 @@ export function TrackRow({
           {showAlbum && ` · ${track.albumTitle}`}
         </div>
       </div>
-      <AvailabilityBadge availability={track.availability} />
+      <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem' }}>
+        <MetadataStatusBadge
+          status={track.metadataStatus}
+          error={track.metadataError}
+        />
+        <AvailabilityBadge availability={track.availability} />
+      </div>
       <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem' }}>
         <span
           style={{