fix: stabilize runtime follow-up regressions

src/lib/mysql-connector.h

@@ -33,6 +33,10 @@ struct MySQL {
 	DTree query(String q, StringMap params);
 	DTree get_pending_result();
 
+	// Unregisters from the request's connection tracking, so stack-allocated
+	// instances cannot leave dangling pointers behind for request cleanup.
+	~MySQL() { disconnect(); }
+
 };
 
 MySQL* mysql_connect(String host = "localhost", String username = "root", String password = "")