feat(docker): add Dockerfile, docker-compose and headless fallback for local testing

docker-compose.yml

@@ -0,0 +1,25 @@
+services:
+  jellyfin-client:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    container_name: jellyfin-client
+    restart: unless-stopped
+    ports:
+      - "8080:8080"  # Kodi JSON-RPC (Yatse)
+      - "9090:9090"  # Kodi JSON-RPC WebSocket
+      - "8097:8097"  # Web Remote & REST API
+    environment:
+      - DISPLAY=${DISPLAY:-:0}
+      - MPV_VO=${MPV_VO:-gpu}          # Change to 'null' for headless test without window
+      - MPV_HWDEC=${MPV_HWDEC:-auto}    # 'auto', 'vaapi', 'nvdec', or 'no'
+      - MPV_FULLSCREEN=${MPV_FULLSCREEN:-false}  # Windowed by default for desktop testing
+    volumes:
+      # Optional: Mount custom config.yaml if present
+      - ./config.yaml:/app/config.yaml:ro
+      # X11 Display passthrough to show video window on host screen
+      - /tmp/.X11-unix:/tmp/.X11-unix:ro
+    # Optional hardware acceleration devices (uncomment if available on Linux host)
+    # devices:
+    #   - /dev/dri:/dev/dri
+    #   - /dev/snd:/dev/snd