fix(mcp): ensure authorization url is valid when containing query params (#5545)

Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/core/src/mcp/oauth-provider.ts

@@ -308,7 +308,11 @@ export class MCPOAuthProvider {
       );
     }
 
-    return `${config.authorizationUrl}?${params.toString()}`;
+    const url = new URL(config.authorizationUrl!);
+    params.forEach((value, key) => {
+      url.searchParams.append(key, value);
+    });
+    return url.toString();
   }
 
   /**