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

agent/chat.go

@@ -92,6 +92,7 @@ func (c *ChatAgent) Chat(ctx context.Context, agentKey, sessionID, message strin
 	// visible skills/MCP and lets the DB tools table filter/override. DefaultTools
 	// have no tools-table rows, so they always pass through.
 	base := actool.DefaultTools()
+	ctx = WithRunInfo(ctx, RunInfo{SessionID: sessionID})
 	tools, def, cleanup := AugmentTools(ctx, agentKey, base)
 	defer cleanup()
 

agent/mainagent.go

@@ -85,6 +85,7 @@ func (m *MainAgent) Chat(ctx context.Context, taskID int64, as *db.AssetStore, t
 	tsx.SetNotifyGoal(notifyGoal) // set_goals 新增目标 → 给 planner 记一条「人新增了目标：…」触发
 	// 领域工具 + 基础默认工具集（Read/Write/Edit/MultiEdit/LS/Glob/Grep/Bash）
 	base := append(tsx.MainAgentTools(), actool.DefaultTools()...)
+	ctx = WithRunInfo(ctx, RunInfo{TaskID: taskID, ExplorationID: explorationID(ts)})
 	tools, def, cleanup := AugmentTools(ctx, "mainagent", base)
 	defer cleanup()
 	// 本任务的工作目录 <workDir>/tasks/<taskID>，先建好。

agent/planner.go

@@ -273,6 +273,7 @@ func (p *Planner) Plan(ctx context.Context, taskID int64, as *db.AssetStore, ts
 	}
 	// 领域工具 + 基础默认工具集（Read/Write/Edit/MultiEdit/LS/Glob/Grep/Bash）
 	base := append(tsx.PlannerTools(), actool.DefaultTools()...)
+	ctx = WithRunInfo(ctx, RunInfo{TaskID: taskID, ExplorationID: explorationID(ts)})
 	tools, def, cleanup := AugmentTools(ctx, "planner", base)
 	defer cleanup()
 	// 关键态势（刚完成的意图 + 预取的完整图）改放【本轮 user 输入】(见下方 input)，system

agent/runinfo.go

@@ -0,0 +1,47 @@
+package agent
+
+import (
+	"context"
+
+	"github.com/Autumn-27/artex/db"
+)
+
+// RunInfo identifies WHICH run a tool call belongs to. Tool assembly only receives
+// (ctx, agentKey) — the task/exploration ids live in the caller's arguments, not the
+// ctx — so anything wired at assembly time (currently the Skill ledger in
+// server/assembly.go) has no way to attribute a call to a task. Each run attaches
+// its own RunInfo before calling AugmentTools; the wiring closure reads it once and
+// captures it, so per-run attribution stays correct without threading parameters
+// through the tool layer. Same pattern as TaskClock (see taskclock.go).
+//
+// Zero value = attribution unknown; every consumer must treat it as optional.
+type RunInfo struct {
+	TaskID        int64  // task registry id; 0 for non-task runs (chat sessions)
+	ExplorationID int64  // exploration id; 0 when unknown
+	IntentID      int64  // worker's intent node; 0 for planner/mainagent/chat
+	SessionID     string // chat conversation id; empty for task runs
+}
+
+// explorationID reads a store's exploration id, tolerating a nil store (planner and
+// worker runs can be driven without one in tests).
+func explorationID(ts *db.ExplorationStore) int64 {
+	if ts == nil {
+		return 0
+	}
+	return ts.ID()
+}
+
+type runInfoKey struct{}
+
+// WithRunInfo attaches run attribution to ctx.
+func WithRunInfo(ctx context.Context, ri RunInfo) context.Context {
+	return context.WithValue(ctx, runInfoKey{}, ri)
+}
+
+// RunInfoFrom reads the RunInfo (zero value if none attached).
+func RunInfoFrom(ctx context.Context) RunInfo {
+	if v, ok := ctx.Value(runInfoKey{}).(RunInfo); ok {
+		return v
+	}
+	return RunInfo{}
+}

agent/worker.go

@@ -265,6 +265,7 @@ func (w *Worker) Execute(ctx context.Context, name string, taskID int64, as *db.
 	// phase, Bash is hidden via Settlement.DisabledTools (no local gating needed).
 	base := append(tsx.WorkerTools(), w.extraTools...)
 	base = append(base, actool.DefaultTools()...)
+	ctx = WithRunInfo(ctx, RunInfo{TaskID: taskID, ExplorationID: explorationID(ts), IntentID: intent.ID})
 	tools, def, cleanup := AugmentTools(ctx, "worker", base)
 	defer cleanup()