feat(intercept): 模型兜底审批单独计量 token 并在配置页展示

兜底审批(LLM judge)调模型判定漏网命令,其 token 消耗此前无法单独查看:
usage 行要么无 worker 归属、要么被并进复用的模型 profile 桶里。

- llmrec 增加 WithWorker 上下文覆盖,reviewer 调用前标注 worker='judge'，
  让审批调用的计量行可被单独筛出(复用现有 llm_usage.worker 列,无需迁移)。
- db.JudgeUsageStats 返回累计总量 + 近 N 天每日序列(WHERE worker='judge')。
- 新增 GET /api/intercept/judge/usage。
- 配置页「模型兜底审批」开关下方新增用量卡片:调用次数 / 输入 / 输出 /
  缓存读写 五项统计 + 近 30 天每日消耗迷你柱图 + 刷新。

db/llm_usage.go

@@ -259,6 +259,70 @@ ORDER BY day`, days)
 	return out, nil
 }
 
+// JudgeDayUsage is one UTC-day token bucket for the intercept fallback judge,
+// for the config page's recent-spend sparkline.
+type JudgeDayUsage struct {
+	Date         string `json:"date"` // YYYY-MM-DD (UTC)
+	Calls        int    `json:"calls"`
+	InputTokens  int    `json:"input_tokens"`
+	OutputTokens int    `json:"output_tokens"`
+}
+
+// JudgeUsage is the cumulative token spend of the intercept fallback judge
+// (worker='judge' rows in the always-on ledger), plus a recent daily series.
+type JudgeUsage struct {
+	Calls            int             `json:"calls"`
+	InputTokens      int             `json:"input_tokens"`
+	OutputTokens     int             `json:"output_tokens"`
+	CacheReadTokens  int             `json:"cache_read_tokens"`
+	CacheWriteTokens int             `json:"cache_write_tokens"`
+	Daily            []JudgeDayUsage `json:"daily"`
+}
+
+// JudgeUsageStats returns the fallback judge's all-time token totals and a
+// per-day series over the past `days` days (default 30). Sourced from the
+// always-on llm_usage ledger, so it is accurate across pool rotation and
+// interrupted/failed judge calls. days only bounds the daily series; totals are
+// all-time.
+func (d *DB) JudgeUsageStats(days int) (JudgeUsage, error) {
+	if days <= 0 {
+		days = 30
+	}
+	var u JudgeUsage
+	err := d.QueryRow(`
+SELECT COUNT(*), COALESCE(SUM(input_tokens),0), COALESCE(SUM(output_tokens),0),
+       COALESCE(SUM(cache_read),0), COALESCE(SUM(cache_write),0)
+FROM llm_usage
+WHERE worker = 'judge'`).Scan(&u.Calls, &u.InputTokens, &u.OutputTokens,
+		&u.CacheReadTokens, &u.CacheWriteTokens)
+	if err != nil {
+		return JudgeUsage{}, err
+	}
+	rows, err := d.Query(`
+SELECT to_char(ts AT TIME ZONE 'UTC', 'YYYY-MM-DD') AS day,
+       COUNT(*), COALESCE(SUM(input_tokens),0), COALESCE(SUM(output_tokens),0)
+FROM llm_usage
+WHERE worker = 'judge' AND ts >= now() - ($1 * interval '1 day')
+GROUP BY day
+ORDER BY day`, days)
+	if err != nil {
+		return JudgeUsage{}, err
+	}
+	defer rows.Close()
+	u.Daily = []JudgeDayUsage{}
+	for rows.Next() {
+		var day JudgeDayUsage
+		if err := rows.Scan(&day.Date, &day.Calls, &day.InputTokens, &day.OutputTokens); err != nil {
+			return JudgeUsage{}, err
+		}
+		u.Daily = append(u.Daily, day)
+	}
+	if err := rows.Err(); err != nil {
+		return JudgeUsage{}, err
+	}
+	return u, nil
+}
+
 // ParseExpID turns the exploration-id segment parsed from a session string into an
 // int64 (0 when empty/non-numeric, e.g. chat sessions keyed by conversation id).
 func ParseExpID(s string) int64 {