feat(skills): 新增 Skill 调用统计（账本 + 页面总览/详情）

后端：
- 新表 skill_usage（无外键，任务/会话删除后统计保留），一次 Skill()
  调用记一行，只记维度不记 args 正文；含 found 标记未命中调用
- 用 RunInfo 经 ctx 把 task/exploration/intent/session 传到工具装配层，
  在 Skill meta-tool 外包一层做埋点（可记 args 长度与不存在的 skill）
- fsListSkills 返回附带调用次数/覆盖任务/最近调用；新增
  GET /api/skills/missing 与 GET /api/skills/{name}/usage

前端（/system/skills）：
- 树节点显示调用次数 badge；目录优先排序 + 子项缩进错开一级
- 空态改为技能库总览（指标卡 + 调用排行 + 最近/未使用）
- 选中 skill 的详情面板改为响应式左右分栏（配置在左、统计在右，
  窄屏回落上下），含最近调用明细与未命中缺口清单

Claude-Session: https://claude.ai/code/session_01BNN7npEJs4X6LfTtgniMd8

web/src/lib/mock/data.ts

@@ -7,7 +7,7 @@ import type {
   Activity, Agent, AgentDetail, Asset, Audit, Company, Conversation,
   ConvTokenSummary, DailyTokenBucket, Edge, Finding, InterceptApprovalRow,
   InterceptPending, InterceptRule, LLMPoolStatus, LLMProfile, MCPServer, MCPTool, PromptVar,
-  PromptVersion, Settings, SkillItem, Stats, TaskNode, Task, TokenTotal,
+  PromptVersion, Settings, SkillCall, SkillItem, MissingSkill, Stats, TaskNode, Task, TokenTotal,
   TokenUsage, Tool, TrafficResp, TrafficDetail, TrafficHost, LLMTask,
 } from "@/lib/types";
 
@@ -686,9 +686,19 @@ export const mcpToolsById: Record<number, MCPTool[]> = {
 
 // ── Skills ───────────────────────────────────────────────────────────────────
 export const skills: SkillItem[] = [
-  { name: "api-recon", description: "对 REST/GraphQL API 做侦察与越权面枚举；发现新 API 端点时使用。", license: "MIT", mcps: [], files: ["SKILL.md", "scripts/enum.py"] },
-  { name: "playwright-cli", description: "用 Playwright 驱动浏览器做动态爬取与截图；需要渲染 JS 站点时使用。", mcps: ["playwright"], files: ["SKILL.md"] },
-  { name: "scopesentry", description: "从 ScopeSentry 拉取资产并归并到公司范围；批量导入资产时使用。", files: ["SKILL.md", "assets/mapping.md"] },
+  { name: "api-recon", description: "对 REST/GraphQL API 做侦察与越权面枚举；发现新 API 端点时使用。", license: "MIT", mcps: [], files: ["SKILL.md", "scripts/enum.py"], calls: 24, tasks: 6, usage_agents: ["worker", "planner"], last_used: "2026-08-20T09:12:00Z" },
+  { name: "playwright-cli", description: "用 Playwright 驱动浏览器做动态爬取与截图；需要渲染 JS 站点时使用。", mcps: ["playwright"], files: ["SKILL.md"], calls: 7, tasks: 3, usage_agents: ["worker"], last_used: "2026-08-19T21:40:00Z" },
+  { name: "scopesentry", description: "从 ScopeSentry 拉取资产并归并到公司范围；批量导入资产时使用。", files: ["SKILL.md", "assets/mapping.md"], calls: 0, tasks: 0, usage_agents: [] },
+];
+
+export const skillCalls: SkillCall[] = [
+  { ts: "2026-08-20T09:12:00Z", agent_key: "worker", task_id: 42, session_id: "", args_len: 128 },
+  { ts: "2026-08-20T08:03:00Z", agent_key: "planner", task_id: 42, session_id: "", args_len: 0 },
+  { ts: "2026-08-19T17:55:00Z", agent_key: "worker", task_id: 37, session_id: "", args_len: 64 },
+];
+
+export const missingSkills: MissingSkill[] = [
+  { skill: "jwt-forge", calls: 3, agents: ["worker"], last_used: "2026-08-20T07:20:00Z" },
 ];
 
 // ── Tools ────────────────────────────────────────────────────────────────────

web/src/lib/mock/handler.ts

@@ -467,6 +467,8 @@ function route(m: string, path: string, seg: string[], q: URLSearchParams, b: Re
 
   // ── skills ──
   if (path === "/skills" && m === "GET") return { skills: D.skills };
+  if (path === "/skills/missing") return { missing: D.missingSkills };
+  if (seg[0] === "skills" && seg[2] === "usage") return { calls: D.skillCalls };
   if (path === "/skills" && m === "POST") return { name: String(b.name ?? "new-skill") };
   if (seg[0] === "skills" && seg[2] === "files" && seg.length === 3) return { files: ["SKILL.md"] };
   if (seg[0] === "skills" && seg[2] === "files" && seg.length >= 4)