Add callbacks support for all media actions

- Add CallbackConfig model for callback scripts
- Add callbacks section to config for optional command execution
- Add turn_on/turn_off/toggle endpoints (callback-only)
- Add callbacks for all media actions (play, pause, stop, next, previous, volume, mute, seek)
- Update README with callbacks documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

media_server/routes/scripts.py

@@ -82,7 +82,6 @@ async def execute_script(
             status_code=status.HTTP_404_NOT_FOUND,
             detail=f"Script '{script_name}' not found. Use /api/scripts/list to see available scripts.",
         )
-
     script_config = settings.scripts[script_name]
     args = request.args if request else []