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/config.py

@@ -10,6 +10,15 @@ from pydantic import BaseModel, Field
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
+class CallbackConfig(BaseModel):
+    """Configuration for a callback script (no label/description needed)."""
+
+    command: str = Field(..., description="Command or script to execute")
+    timeout: int = Field(default=30, description="Execution timeout in seconds", ge=1, le=300)
+    working_dir: Optional[str] = Field(default=None, description="Working directory")
+    shell: bool = Field(default=True, description="Run command in shell")
+
+
 class ScriptConfig(BaseModel):
     """Configuration for a custom script."""
 
@@ -47,6 +56,12 @@ class Settings(BaseSettings):
         default=1.0, description="Media status poll interval in seconds"
     )
 
+    # Audio device settings
+    audio_device: Optional[str] = Field(
+        default=None,
+        description="Audio device name to control (None = default device). Use /api/audio/devices to list available devices.",
+    )
+
     # Logging
     log_level: str = Field(default="INFO", description="Logging level")
 
@@ -56,6 +71,12 @@ class Settings(BaseSettings):
         description="Custom scripts that can be executed via API",
     )
 
+    # Callback scripts (executed by integration events, not shown in UI)
+    callbacks: dict[str, CallbackConfig] = Field(
+        default_factory=dict,
+        description="Callback scripts executed by integration events (on_turn_on, on_turn_off, on_toggle)",
+    )
+
     @classmethod
     def load_from_yaml(cls, path: Optional[Path] = None) -> "Settings":
         """Load settings from a YAML configuration file."""
@@ -110,6 +131,9 @@ def generate_default_config(path: Optional[Path] = None) -> Path:
         "api_token": secrets.token_urlsafe(32),
         "poll_interval": 1.0,
         "log_level": "INFO",
+        # Audio device to control (use GET /api/audio/devices to list available devices)
+        # Set to null or remove to use default device
+        # "audio_device": "Speakers (Realtek",
         "scripts": {
             "example_script": {
                 "command": "echo Hello from Media Server!",