refactor(ui): Lucide migration unit 2 — Icons.* -> LucideIcons.* sweep (#60)

Mechanical sweep across 30 files: every Material Icons.* replaced with
the signed-off Lucide equivalent + a flutter_lucide import per file.
Zero Material Icons.* remain in lib/; no unused imports.

Judgment-call mappings: album->disc_3, library_music->library_big,
playlist_play->list_video, graphic_eq->audio_lines,
system_update->download, restore->archive_restore,
download_done->circle_check_big.

track_actions_sheet like menu row: collapsed `liked ? favorite :
favorite_border` to a single LucideIcons.heart (the row's Like/Unlike
text label conveys state). Icon-only LikeButton + the notification keep
the filled-vs-outline shape per the design decision.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

flutter_client/lib/player/queue_screen.dart

@@ -1,5 +1,6 @@
 import 'package:audio_service/audio_service.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_lucide/flutter_lucide.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
@@ -20,7 +21,7 @@ class QueueScreen extends ConsumerWidget {
         backgroundColor: fs.obsidian,
         elevation: 0,
         leading: IconButton(
-          icon: Icon(Icons.arrow_back, color: fs.parchment),
+          icon: Icon(LucideIcons.arrow_left, color: fs.parchment),
           onPressed: () => context.pop(),
         ),
         title: Text('Queue', style: TextStyle(color: fs.parchment)),
@@ -84,7 +85,7 @@ class _QueueRow extends StatelessWidget {
           if (isCurrent)
             Padding(
               padding: const EdgeInsets.only(right: 8),
-              child: Icon(Icons.graphic_eq, color: fs.accent, size: 16),
+              child: Icon(LucideIcons.audio_lines, color: fs.accent, size: 16),
             ),
           Expanded(
             child: Column(