fix: 7 bug fixes + port config with auto-restart

- HTTPException import added (was causing 500 on missing dashboard)
- game_manager.remove_plugin() restored (was AttributeError)
- api.js checks HTTP status codes, fails fast on errors
- sidebar game highlight only matches selected gameId
- scene resize handler uses stored canvas dims (was NaN)
- forwarder socket properly closed on listener stop
- telemetry port: use_unified_port toggle, off = per-game port, auto-restart on switch

server/telemetry/listener.py

@@ -115,6 +115,9 @@ class TelemetryListener:
         if self._transport:
             self._transport.close()
             self._transport = None
+        if self.forwarder._sock:
+            self.forwarder._sock.close()
+            self.forwarder._sock = None
         logger.info("Telemetry listener stopped")
 
     def _get_parser(self, key: str) -> BaseParser: