Add turn_on/turn_off/toggle support

- Add API_TURN_ON, API_TURN_OFF, API_TOGGLE constants
- Add turn_on(), turn_off(), toggle() methods to MediaServerClient
- Implement async_turn_on, async_turn_off, async_toggle in media player
- Add TURN_ON and TURN_OFF to supported features
- Update README with turn on/off/toggle documentation

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

custom_components/remote_media_player/api_client.py

@@ -22,6 +22,9 @@ from .const import (
     API_VOLUME,
     API_MUTE,
     API_SEEK,
+    API_TURN_ON,
+    API_TURN_OFF,
+    API_TOGGLE,
     API_SCRIPTS_LIST,
     API_SCRIPTS_EXECUTE,
 )
@@ -245,6 +248,30 @@ class MediaServerClient:
         """
         return await self._request("POST", API_SEEK, {"position": position})
 
+    async def turn_on(self) -> dict[str, Any]:
+        """Send turn on command.
+
+        Returns:
+            Response data
+        """
+        return await self._request("POST", API_TURN_ON)
+
+    async def turn_off(self) -> dict[str, Any]:
+        """Send turn off command.
+
+        Returns:
+            Response data
+        """
+        return await self._request("POST", API_TURN_OFF)
+
+    async def toggle(self) -> dict[str, Any]:
+        """Send toggle command.
+
+        Returns:
+            Response data
+        """
+        return await self._request("POST", API_TOGGLE)
+
     async def list_scripts(self) -> list[dict[str, Any]]:
         """List available scripts on the server.