feat: add SFX volume control and improve audio feedback

- Implemented separate sound effects volume control in settings.
- Updated backend to handle new `sfx_volume` parameter.
- Enhanced UI to include sound effects volume slider in admin panel.
- Integrated sound effects for various user interactions (clicks, navigation, alerts).
- Added a new global sound engine to manage audio synthesis without external files.
- Updated documentation for Docker deployment and Windows packaging.
- Refactored audio context management to ensure sound effects are available post user interaction.

backend/app/storage.py

@@ -12,6 +12,7 @@ DEFAULT_SETTINGS = {
     "username": "admin",
     "password": "123456",
     "volume": 80,
+    "sfx_volume": 60,
     "auto_play": True,
     "play_mode": "sequential",
     "image_duration": 5,