feat: 工具/技能调用统计 + 用户活动审计 + 标签多选筛选

- 任务1: 用户管理/定时任务管理移入左下角菜单, 从侧边栏删除原入口
- 任务2: 管理员查看用户问答(读 LangGraph checkpoint)与记忆, 新增 admin_users 路由与审计页
- 任务3: 标签筛选改为顶部多选标签栏(OR), agents/skills/scheduled_tasks 三端
- 任务4: 新增 tool_call_metrics 表 + ToolMetricsMiddleware + tool-metrics 路由,
  工具/技能调用统计并入大模型统计页, 含错误分类
- 技能识别: lead agent 经 read_file 加载 /mnt/skills/<cat>/<name>/SKILL.md 调用技能,
  中间件扫描工具参数里的 skills/{public,custom}/{name}/ 路径还原 skill_name
- 单元测试 tests/test_tool_metrics_middleware.py (18 项全过)
- 附: SQLite->MySQL 切换后清理脚本

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend-web/src/core/admin/api.ts

@@ -0,0 +1,72 @@
+import { apiFetch } from "@/core/api";
+import { getBackendBaseURL } from "@/core/config";
+
+/** A conversation thread owned by some user (admin view). */
+export interface AdminThread {
+  thread_id: string;
+  display_name: string;
+  status: string;
+  created_at: string;
+  updated_at: string;
+}
+
+/**
+ * One conversation message, as serialized from the LangGraph checkpoint —
+ * a LangChain message dump: ``type`` is "human" | "ai" | "tool" | "system",
+ * ``content`` is a string or a content-block list.
+ */
+export interface AdminMessage {
+  type?: string;
+  content?: unknown;
+  id?: string | null;
+  name?: string | null;
+}
+
+/** One memory bucket: the global file or a per-agent file. */
+export interface AdminMemoryBucket {
+  name: string;
+  data: Record<string, unknown>;
+}
+
+export interface AdminMemoryResponse {
+  user_id: string;
+  buckets: AdminMemoryBucket[];
+}
+
+const base = () => `${getBackendBaseURL()}/api/admin/users`;
+
+async function parse<T>(res: Response, what: string): Promise<T> {
+  if (!res.ok) {
+    const err = (await res.json().catch(() => ({}))) as { detail?: string };
+    throw new Error(err.detail ?? `${what} (HTTP ${res.status})`);
+  }
+  return res.json() as Promise<T>;
+}
+
+export async function listUserThreads(userId: string): Promise<AdminThread[]> {
+  return parse(
+    await apiFetch(`${base()}/${encodeURIComponent(userId)}/threads?limit=200`),
+    "Failed to load threads",
+  );
+}
+
+export async function listUserThreadMessages(
+  userId: string,
+  threadId: string,
+): Promise<AdminMessage[]> {
+  return parse(
+    await apiFetch(
+      `${base()}/${encodeURIComponent(userId)}/threads/${encodeURIComponent(threadId)}/messages`,
+    ),
+    "Failed to load messages",
+  );
+}
+
+export async function getUserMemory(
+  userId: string,
+): Promise<AdminMemoryResponse> {
+  return parse(
+    await apiFetch(`${base()}/${encodeURIComponent(userId)}/memory`),
+    "Failed to load memory",
+  );
+}