Fix transport_security blocking non-localhost bindings

When binding to a non-localhost host, FastMCP's auto-set restrictive
transport_security causes external connections to be rejected with 421.
Reset it to None so hosts like host.docker.internal are accepted.

server.py

@@ -532,6 +532,11 @@ if __name__ == "__main__":
     args = parser.parse_args()
     if args.host:
         mcp.settings.host = args.host
+        if args.host not in ("127.0.0.1", "localhost", "::1"):
+            # FastMCP auto-sets restrictive transport_security for localhost at init time.
+            # Reset it when binding to a non-localhost address so external hosts
+            # (e.g. host.docker.internal) are not rejected with 421.
+            mcp.settings.transport_security = None
     if args.port:
         mcp.settings.port = args.port
     mcp.run(transport=args.transport)