feat(waf): 新增 UA 检查节点 ua_check

支持要求携带 UA、浏览器/OS 白名单 and-or 匹配，以及优先屏蔽爬虫与非正常 UA。

frontend/lib/services/openflare/types.ts

@@ -779,6 +779,15 @@ export interface BlockNodeConfig {
   response_body: string;
 }
 
+export interface UACheckConfig {
+  require_ua: boolean;
+  browsers: string[];
+  operating_systems: string[];
+  match_mode: 'and' | 'or';
+  block_common_bots: boolean;
+  block_abnormal_ua: boolean;
+}
+
 export type WAFRuleNode =
   | {
       id: string;
@@ -801,6 +810,13 @@ export type WAFRuleNode =
       position: XYPosition;
       config: GeoMatchConfig;
     }
+  | {
+      id: string;
+      type: 'ua_check';
+      label?: string;
+      position: XYPosition;
+      config: UACheckConfig;
+    }
   | {
       id: string;
       type: 'pow';