fix: verify token on --auth and broaden startup exception catch

server.py

@@ -162,13 +162,14 @@ async def _run_server() -> None:
 if __name__ == "__main__":
     if "--auth" in sys.argv:
         print("Authenticating with Spotify (a browser window will open)...")
-        spotify_client.get_client()
+        sp = spotify_client.get_client()
+        sp.current_user()  # verify the token actually works
         print("Authentication successful! Token cached.")
         sys.exit(0)
 
     try:
         spotify_client.get_client()
-    except RuntimeError as e:
+    except Exception as e:
         print(f"Startup error: {e}", file=sys.stderr)
         sys.exit(1)