fix(flutter): tighter track row + missing artist in mini player + hide redundant artist on artist page

Track row (album detail):
- Vertical padding 10→6 and only render the artist line when non-empty,
  so tracks without a populated artist row don't reserve a blank line.
- Number column 28→22 — visually tighter without making 3-digit
  numbers cramp.

Mini player missing artist:
- Symptom was an empty `artist` field on MediaItem after tapping a
  track in album detail; layout change wasn't the cause. Real cause:
  albumProvider's cold-cache only wrote cachedAlbums + cachedTracks,
  never cachedArtists. The drift JOINs that build the AlbumRef + each
  TrackRef returned null for the artist row, so artistName fell back
  to '' and the audio handler stamped MediaItem.artist=''.
- Cold-cache now collects every distinct (artistId, artistName) pair
  off the album header + each track, inserts them into cachedArtists
  alongside the album/tracks. Subsequent JOINs populate artistName,
  the audio handler stamps it on MediaItem, and the mini player picks
  it up via the existing artistName.isNotEmpty render.
- Existing cached albums won't get artist names until they're
  re-fetched (cache invalidation TBD). Future cold-cache hits will.

Artist detail album grid:
- AlbumCard gains showArtist (default true). Pass false in the artist
  detail grid since the page header already names the artist. cellH
  trimmed by the 16dp artist line.

flutter_client/lib/library/artist_detail_screen.dart

@@ -89,8 +89,10 @@ class ArtistDetailScreen extends ConsumerWidget {
                   (constraints.maxWidth - sidePad * 2 - gap * (cols - 1)) /
                       cols;
               // Card content: cover (cellW - 16) + 8 + title (≤2 lines
-              // ≈ 36) + artist line ≈ 16 + small fudge.
-              final cellH = (cellW - 16) + 8 + 36 + 16 + 4;
+              // ≈ 36) + small fudge. Artist line is suppressed in this
+              // grid (showArtist: false) since the page header already
+              // names the artist.
+              final cellH = (cellW - 16) + 8 + 36 + 4;
               return GridView.builder(
                 shrinkWrap: true,
                 physics: const NeverScrollableScrollPhysics(),
@@ -108,6 +110,7 @@ class ArtistDetailScreen extends ConsumerWidget {
                     album: album,
                     width: cellW,
                     titleMaxLines: 2,
+                    showArtist: false,
                     onTap: () => context.push('/albums/${album.id}'),
                   );
                 },

flutter_client/lib/library/library_providers.dart

@@ -179,7 +179,35 @@ final albumProvider = StreamProvider.family<
               .getAlbum(albumId)
               .timeout(const Duration(seconds: 10));
           debugPrint('albumProvider($albumId): got ${fresh.tracks.length} tracks, writing to drift');
+          // Collect every artist mentioned by the album + its tracks so
+          // the JOINs that drive both the album header and the track
+          // rows have something to bind to. Without this, drift returns
+          // null for the artist row and artistName surfaces empty —
+          // visible as a missing artist line in the mini player and
+          // the row list.
+          final artists = <String, ArtistRef>{};
+          if (fresh.album.artistId.isNotEmpty &&
+              fresh.album.artistName.isNotEmpty) {
+            artists[fresh.album.artistId] = ArtistRef(
+              id: fresh.album.artistId,
+              name: fresh.album.artistName,
+            );
+          }
+          for (final t in fresh.tracks) {
+            if (t.artistId.isNotEmpty &&
+                t.artistName.isNotEmpty &&
+                !artists.containsKey(t.artistId)) {
+              artists[t.artistId] = ArtistRef(
+                id: t.artistId,
+                name: t.artistName,
+              );
+            }
+          }
           await db.batch((b) {
+            if (artists.isNotEmpty) {
+              b.insertAllOnConflictUpdate(
+                  db.cachedArtists, artists.values.map((a) => a.toDrift()).toList());
+            }
             b.insertAllOnConflictUpdate(db.cachedAlbums, [fresh.album.toDrift()]);
             b.insertAllOnConflictUpdate(db.cachedTracks,
                 fresh.tracks.map((t) => t.toDrift()).toList());

flutter_client/lib/library/widgets/album_card.dart

@@ -11,6 +11,7 @@ class AlbumCard extends StatelessWidget {
     required this.onTap,
     this.width = 140,
     this.titleMaxLines = 1,
+    this.showArtist = true,
     super.key,
   });
   final AlbumRef album;
@@ -26,6 +27,10 @@ class AlbumCard extends StatelessWidget {
   /// ellipsized character at narrower widths.
   final int titleMaxLines;
 
+  /// Suppress the artist name. Useful on surfaces where the artist is
+  /// already implied by the page header (e.g. artist detail).
+  final bool showArtist;
+
   @override
   Widget build(BuildContext context) {
     final fs = Theme.of(context).extension<FabledSwordTheme>()!;
@@ -61,12 +66,13 @@ class AlbumCard extends StatelessWidget {
                   overflow: TextOverflow.ellipsis,
                   style: TextStyle(color: fs.parchment, fontSize: 14),
                 ),
-                Text(
-                  album.artistName,
-                  maxLines: 1,
-                  overflow: TextOverflow.ellipsis,
-                  style: TextStyle(color: fs.ash, fontSize: 12),
-                ),
+                if (showArtist && album.artistName.isNotEmpty)
+                  Text(
+                    album.artistName,
+                    maxLines: 1,
+                    overflow: TextOverflow.ellipsis,
+                    style: TextStyle(color: fs.ash, fontSize: 12),
+                  ),
               ],
             ),
           ),

flutter_client/lib/library/widgets/track_row.dart

@@ -30,31 +30,39 @@ class TrackRow extends StatelessWidget {
     return InkWell(
       onTap: onTap,
       child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 6),
         child: Row(children: [
           if (track.trackNumber != null)
             SizedBox(
-              width: 28,
+              width: 22,
               child: Text(
                 track.trackNumber.toString(),
                 style: TextStyle(color: fs.ash, fontSize: 13),
               ),
             ),
           Expanded(
-            child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
-              Text(
-                track.title,
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
-                style: TextStyle(color: fs.parchment, fontSize: 14),
-              ),
-              Text(
-                track.artistName,
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
-                style: TextStyle(color: fs.ash, fontSize: 12),
-              ),
-            ]),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                Text(
+                  track.title,
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                  style: TextStyle(color: fs.parchment, fontSize: 14),
+                ),
+                // Skip the artist line entirely when empty so the row
+                // height collapses to a single line of title — keeps
+                // dense album views from looking padded.
+                if (track.artistName.isNotEmpty)
+                  Text(
+                    track.artistName,
+                    maxLines: 1,
+                    overflow: TextOverflow.ellipsis,
+                    style: TextStyle(color: fs.ash, fontSize: 12),
+                  ),
+              ],
+            ),
           ),
           CachedIndicator(trackId: track.id),
           Text('$mins:$secs', style: TextStyle(color: fs.ash, fontSize: 12)),