Initial commit: Media server and Home Assistant integration

- FastAPI server for Windows media control via WinRT/SMTC
- Home Assistant custom integration with media player entity
- Script button entities for system commands
- Position tracking with grace period for track skip handling
- Server availability detection in HA entity

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

media_server/models/__init__.py

@@ -0,0 +1,17 @@
+"""Pydantic models for the media server API."""
+
+from .media import (
+    MediaState,
+    MediaStatus,
+    VolumeRequest,
+    SeekRequest,
+    MediaInfo,
+)
+
+__all__ = [
+    "MediaState",
+    "MediaStatus",
+    "VolumeRequest",
+    "SeekRequest",
+    "MediaInfo",
+]