feat(harness): add readonly mysql tool

src/main/resources/application.yml

@@ -200,3 +200,9 @@ logging:
       max-file-size: 10MB  # 单个日志文件最大 10MB
       max-history: 30  # 保留 30 天
       total-size-cap: 1GB  # 所有日志文件总大小上限 1GB
+
+# Agent-facing MySQL Tool uses independent logical datasources only.
+# Production entries are supplied by a dedicated profile and Secret injection.
+harness:
+  mysql-tools:
+    data-sources: {}