Redesign UI with Vuetify and improve configuration

Major changes:
- Full UI redesign with Vuetify 3 (dark theme, modern components)
- Sidebar navigation with gradient logo
- Redesigned player controls with Material Design icons
- New room cards, track lists, and filter UI with chips
- Modern auth pages with centered cards

Configuration improvements:
- Centralized all settings in root .env file
- Removed redundant backend/.env and frontend/.env files
- Increased file upload limit to 100MB (nginx + backend)
- Added build args for Vite environment variables
- Frontend now uses relative paths (better for domain deployment)

UI Components updated:
- App.vue: v-navigation-drawer with sidebar
- MiniPlayer: v-footer with modern controls
- Queue: v-list with styled items
- RoomView: improved filters with clickable chips
- All views: Vuetify cards, buttons, text fields

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.env.example

@@ -14,5 +14,11 @@ S3_BUCKET_NAME=enigfm
 S3_REGION=ru-1
 
 # Limits
-MAX_FILE_SIZE_MB=10
+MAX_FILE_SIZE_MB=100
 MAX_STORAGE_GB=90
+MAX_ROOM_PARTICIPANTS=50
+
+# Frontend (Vite)
+# VITE_API_URL - оставляем пустым для использования относительных путей
+# VITE_WS_URL - оставляем пустым для автоопределения
+VITE_MAX_FILE_SIZE_MB=100