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/player_bar.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 import 'package:audio_service/audio_service.dart';
 import 'package:cached_network_image/cached_network_image.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';
 
@@ -229,7 +230,7 @@ class _PlayControls extends StatelessWidget {
           child: IconButton(
             padding: EdgeInsets.zero,
             iconSize: 22,
-            icon: Icon(Icons.skip_previous, color: fs.parchment),
+            icon: Icon(LucideIcons.skip_back, color: fs.parchment),
             onPressed: () => ref.read(audioHandlerProvider).skipToPrevious(),
           ),
         ),
@@ -240,7 +241,7 @@ class _PlayControls extends StatelessWidget {
             padding: EdgeInsets.zero,
             iconSize: 32,
             icon: Icon(
-              isPlaying ? Icons.pause_circle_filled : Icons.play_circle_filled,
+              isPlaying ? LucideIcons.circle_pause : LucideIcons.circle_play,
               color: fs.accent,
             ),
             onPressed: () {
@@ -259,7 +260,7 @@ class _PlayControls extends StatelessWidget {
           child: IconButton(
             padding: EdgeInsets.zero,
             iconSize: 22,
-            icon: Icon(Icons.skip_next, color: fs.parchment),
+            icon: Icon(LucideIcons.skip_forward, color: fs.parchment),
             onPressed: () => ref.read(audioHandlerProvider).skipToNext(),
           ),
         ),