fix: port-in-use check and remove packaging dependency

media_server/main.py

@@ -2,6 +2,7 @@
 
 import argparse
 import logging
+import socket
 import sys
 from contextlib import asynccontextmanager
 from pathlib import Path
@@ -259,6 +260,19 @@ def main():
             print("\nAuthentication is DISABLED (no tokens configured)")
         return
 
+    # Check if port is available before starting
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+        try:
+            sock.bind((args.host if args.host != "0.0.0.0" else "127.0.0.1", args.port))
+        except OSError:
+            print(
+                f"ERROR: Port {args.port} is already in use. "
+                f"Another instance of Media Server may be running.\n"
+                f"Stop the other process or use --port to pick a different port.",
+                file=sys.stderr,
+            )
+            sys.exit(1)
+
     from .tray import PYSTRAY_AVAILABLE, TrayManager
 
     use_tray = PYSTRAY_AVAILABLE and not args.no_tray