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/features/upload/UploadPage.tsx

@@ -1,4 +1,4 @@
-import { useRef, useState } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import { useNavigate } from 'react-router';
 import { useTranslation } from 'react-i18next';
 import { Badge, Button, Callout, ScrollArea, Spinner } from '@olly/modern-sk';
@@ -6,6 +6,8 @@ import {
   buildUploadFormData,
   useUploadTrackMutation,
 } from '../../api/endpoints/upload';
+import { useGetTrackQuery } from '../../api/endpoints/library';
+import { MetadataStatusBadge } from '../../components/track/MetadataStatusBadge';
 
 /** Pure client-side state — this is a transient upload queue, never server data. */
 type ItemStatus = 'queued' | 'uploading' | 'done' | 'duplicate' | 'error';
@@ -273,11 +275,7 @@ function UploadRow({
             {item.error}
           </div>
         )}
-        {done && (
-          <div style={{ fontSize: '0.75rem', color: 'var(--color-text-3)' }}>
-            {t('upload.unknownArtist')}
-          </div>
-        )}
+        {done && item.trackId && <EnrichmentStatus trackId={item.trackId} />}
       </div>
 
       <StatusBadge status={item.status} />
@@ -301,6 +299,59 @@ function UploadRow({
   );
 }
 
+/**
+ * Polls a just-uploaded track until enrichment settles, then shows the outcome.
+ * Metadata enrichment runs asynchronously in a worker after the upload response
+ * returns, so without polling the row would never reflect the resolved title/
+ * artist or a failure reason. Polling stops (interval → 0) once the status
+ * leaves `pending`.
+ */
+function EnrichmentStatus({ trackId }: { trackId: string }) {
+  const { t } = useTranslation();
+  const [pollMs, setPollMs] = useState(2500);
+  const { data } = useGetTrackQuery(trackId, { pollingInterval: pollMs });
+
+  useEffect(() => {
+    if (data && data.metadataStatus !== 'pending') setPollMs(0);
+  }, [data]);
+
+  const status = data?.metadataStatus ?? 'pending';
+  const resolved =
+    data && data.metadataStatus === 'enriched'
+      ? `${data.artistName} · ${data.title}`
+      : t(`metadata.statusHint.${status}`);
+
+  return (
+    <div
+      style={{
+        display: 'flex',
+        alignItems: 'center',
+        gap: '0.5rem',
+        marginTop: '0.25rem',
+      }}
+    >
+      <MetadataStatusBadge
+        status={status}
+        error={data?.metadataError}
+        hideWhenEnriched={false}
+      />
+      <span
+        style={{
+          fontSize: '0.75rem',
+          color: 'var(--color-text-3)',
+          overflow: 'hidden',
+          textOverflow: 'ellipsis',
+          whiteSpace: 'nowrap',
+        }}
+      >
+        {status === 'failed' && data?.metadataError
+          ? data.metadataError
+          : resolved}
+      </span>
+    </div>
+  );
+}
+
 function StatusBadge({ status }: { status: ItemStatus }) {
   const { t } = useTranslation();
   if (status === 'uploading') {