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/routers.py

@@ -38,6 +38,7 @@ def _media_type(path):
 
 class SettingsBody(BaseModel):
     volume: int | None = None
+    sfx_volume: int | None = None
     play_mode: str | None = None
     image_duration: int | None = None
     fullscreen: bool | None = None
@@ -106,7 +107,7 @@ async def login(request: Request):
 @router.get("/api/settings")
 async def get_settings():
     s = storage.get_settings()
-    return {k: s[k] for k in ("volume", "play_mode", "image_duration", "fullscreen", "autostart")}
+    return {k: s[k] for k in ("volume", "sfx_volume", "play_mode", "image_duration", "fullscreen", "autostart")}
 
 
 @router.get("/api/config")
@@ -135,7 +136,9 @@ async def runtime_config():
 async def update_settings(body: SettingsBody):
     storage.update_settings(**body.model_dump(exclude_none=True))
     s = storage.get_settings()
-    hub.publish_command("settings_changed", {"volume": s["volume"], "play_mode": s["play_mode"]})
+    hub.publish_command("settings_changed", {
+        "volume": s["volume"], "sfx_volume": s["sfx_volume"], "play_mode": s["play_mode"],
+    })
     return {"ok": True}