fix(flutter): player bar layout, system playlist tap, banner height

Player bar: drop the volume slider — phone hardware controls volume.
Right cluster collapses to a single row of shuffle/repeat/queue.

Playlist card: GestureDetector defers to children by default, so taps
over the cover image area didn't always register. Add HitTestBehavior.opaque
so the whole card surface is tappable.

Update banner: was 3-4× the height of its text — IconButton's default
48dp tap target plus generous vertical padding dominated. Tighten
padding (8→4), shrink dismiss button to 32×32 with iconSize 16, slim
the action button to 28dp height with shrinkWrap tap target.

Home screen: ClampingScrollPhysics + 140dp bottom padding (already
applied in working tree) so scroll stops just above the mini-player.

flutter_client/lib/library/home_screen.dart

@@ -58,20 +58,30 @@ class HomeScreen extends ConsumerWidget {
           ),
           data: (h) => RefreshIndicator(
             onRefresh: () async => ref.refresh(homeProvider.future),
-            child: ListView(children: [
-              _PlaylistsSection(
-                playlists: allPlaylists.value?.owned ?? const [],
-                status: status.value ?? SystemPlaylistsStatus.empty(),
-              ),
-              _RecentlyAddedSection(albums: h.recentlyAddedAlbums),
-              _RediscoverSection(
-                albums: h.rediscoverAlbums,
-                artists: h.rediscoverArtists,
-              ),
-              _MostPlayedSection(tracks: h.mostPlayedTracks),
-              _LastPlayedSection(artists: h.lastPlayedArtists),
-              const SizedBox(height: 96),
-            ]),
+            child: ListView(
+              // ClampingScrollPhysics: no bounce overscroll past the
+              // content. Combined with the bottom padding below, this
+              // makes "scroll to end" land the last item just above the
+              // player bar — no empty void.
+              physics: const ClampingScrollPhysics(),
+              children: [
+                _PlaylistsSection(
+                  playlists: allPlaylists.value?.owned ?? const [],
+                  status: status.value ?? SystemPlaylistsStatus.empty(),
+                ),
+                _RecentlyAddedSection(albums: h.recentlyAddedAlbums),
+                _RediscoverSection(
+                  albums: h.rediscoverAlbums,
+                  artists: h.rediscoverArtists,
+                ),
+                _MostPlayedSection(tracks: h.mostPlayedTracks),
+                _LastPlayedSection(artists: h.lastPlayedArtists),
+                // Bottom padding ≈ player bar height (top row 80 + seek
+                // 30 + padding 16 ≈ ~140) so the last section's bottom
+                // edge lands right above the player when scrolled.
+                const SizedBox(height: 140),
+              ],
+            ),
           ),
         ),
       ),