feat: Modernisation UI/UX et configuration Flutter multi-plateforme

Phase 1 - Corrections Critiques:
- Fixed memory leaks dans music_provider.dart (stream subscriptions)
- Fixed race conditions dans search_provider.dart (stale results)
- Fixed token refresh errors dans api_service.dart
- Improved error handling avec messages utilisateur
- Changed API URL to HTTPS by default

Phase 2 - Améliorations UX Desktop:
- Ajouté cursor pointers sur tous les éléments cliquables
- Implémenté hover states avec effets néon glow (200ms transitions)
- Créé skeleton loading states avec shimmer animation
- Ajouté widgets: ClickableWrapper, ErrorDisplay, SkeletonLoading
- Enhanced visual feedback pour desktop users

Phase 3 - Configuration Flutter:
- Configuré Android (Gradle 8.1.0, Kotlin 1.9.0, minSdk 21, targetSdk 34)
- Créé launcher icons cyberpunk néon (5 densités)
- Configuré Windows desktop (structure complète)
- Activé Linux desktop support
- Ajouté package équatable pour entités de domaine
- Corrigé imports (colors.dart, auth_provider.dart)
- Fixed Dio API compatibility (RequestOptions)

Documentation:
- STYLE_GUIDE.md: Guide complet (100+ pages)
- DESIGN_IMPLEMENTATION_GUIDE.md: Implémentation Flutter
- BUILD_STATUS.md: Status builds + troubleshooting
- QUICKSTART_BUILDS.md: Guide rapide
- BUILD_INDEX.md: Index documentation
- PHASE_1_CORRECTIONS.md: Corrections Phase 1
- PHASE_2_UX_IMPROVEMENTS.md: Améliorations Phase 2
- PR_REVIEW_SUMMARY.md: Revue code complète
- CODE_ANALYSIS_AND_PRIORITIES.md: Analyse code

Scripts & Builds:
- BUILD_ALL.sh: Script automatisé builds multi-plateforme
- builds/: Structure avec README par plateforme
- design-system/: Système de design complet

Backend:
- Ajouté streaming HTTP Range pour audio progressif
- Enhanced YouTube service avec métadonnées complètes
- Improved error handling et validation

Generated with [Claude Code](https://claude.com/claude-code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

frontend/lib/presentation/providers/search_provider.dart

@@ -2,6 +2,7 @@
 library;
 
 import 'dart:async';
+import 'package:flutter/foundation.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../../infrastructure/datasources/remote/music_api_service.dart';
@@ -71,6 +72,9 @@ class SearchNotifier extends StateNotifier<SearchState> {
   }
 
   Future<void> _performSearch(String query) async {
+    // Store the original query to check for race conditions
+    final originalQuery = query;
+
     try {
       final results = await _musicApiService.search(
         query,
@@ -78,29 +82,40 @@ class SearchNotifier extends StateNotifier<SearchState> {
         limit: 20,
       );
 
-      state = SearchState(
-        query: query,
-        tracks: (results['tracks'] as List?)
-                ?.map((json) => Track.fromJson(json as Map<String, dynamic>))
-                .toList() ??
-            [],
-        artists: (results['artists'] as List?)
-                ?.map((json) => Artist.fromJson(json as Map<String, dynamic>))
-                .toList() ??
-            [],
-        albums: (results['albums'] as List?)
-                ?.map((json) => Album.fromJson(json as Map<String, dynamic>))
-                .toList() ??
-            [],
-      );
+      // CRITICAL: Only update state if this is still the current search query
+      // This prevents race conditions where old search results overwrite newer ones
+      if (state.query == originalQuery) {
+        state = SearchState(
+          query: query,
+          tracks: (results['tracks'] as List?)
+                  ?.map((json) => Track.fromJson(json as Map<String, dynamic>))
+                  .toList() ??
+              [],
+          artists: (results['artists'] as List?)
+                  ?.map((json) => Artist.fromJson(json as Map<String, dynamic>))
+                  .toList() ??
+              [],
+          albums: (results['albums'] as List?)
+                  ?.map((json) => Album.fromJson(json as Map<String, dynamic>))
+                  .toList() ??
+              [],
+        );
+      } else {
+        // This search result is stale, ignore it
+        debugPrint('Ignoring stale search results for "$originalQuery" (current: "${state.query}")');
+      }
     } catch (e) {
-      state = SearchState(
-        query: query,
-        error: e.toString(),
-      );
+      // Only update error state if this is still the current query
+      if (state.query == originalQuery) {
+        debugPrint('Search failed for "$originalQuery": $e');
+        state = SearchState(
+          query: query,
+          error: e.toString(),
+        );
+      }
     } finally {
-      // Keep isSearching false if this was the latest search
-      if (state.query == query) {
+      // Only clear loading state if this is still the current query
+      if (state.query == originalQuery) {
         state = state.copyWith(isSearching: false);
       }
     }