feat(ai): 设置里加「AI 生成队列」，看得见后台在算什么

队列本来是完全不可见的：页面上一句「排队生成中」说不出自己是下一个、第二十
个，还是已经放弃了——网关挂掉的时候，「还在生成」和「永远不会好」长得一模
一样。今天排查就是这么排的。

- GET /analysis/insight/queue 返回队列（running 在前，其次按优先级和年龄，
  和 worker 实际取任务的顺序一致）、已生成的解读、scope 名到中文标签的映射
  （前端不必再抄一份），以及消费者的限流配置
- POST /analysis/insight/queue/retry：手动把「已放弃」的重新排队，不等冷却。
  自动重试要等冷却是为了不去捶一个正在抽风的上游；人按下重试是他自己判断值得
  再试一次
- 页面在 设置 → AI 生成队列。插队的任务标「插队」——这是整个界面最想让人看见
  的一件事：为什么是它排在最前面
- 「已生成」单独列：队列空了意味着「没有待办」，不是「什么都没生成过」，
  没有这一节这两件事在界面上没法区分

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/services/jobs.py

@@ -197,6 +197,60 @@ def status_of(user_id, kind, subject):
     }
 
 
+def list_jobs(user_id, limit=60):
+    """The queue as it stands, for the 设置 screen.
+
+    Ordered the way the worker will actually take them — priority, then age —
+    so the list reads as "what happens next" rather than as a table of rows.
+    Finished jobs come last: they are history, not queue.
+    """
+    rows = query_all(
+        "SELECT * FROM ai_jobs WHERE user_id = ? "
+        "ORDER BY CASE status WHEN 'running' THEN 0 WHEN 'pending' THEN 1 "
+        "WHEN 'failed' THEN 2 ELSE 3 END, priority ASC, created_at ASC",
+        [user_id],
+    )
+    return [{
+        "kind": r["kind"],
+        "subject": r["subject"],
+        "status": r["status"],
+        "priority": r["priority"],
+        # The queue only distinguishes "the user is looking at this" from
+        # "backfill"; showing the raw number would mean explaining the scale.
+        "interactive": r["priority"] <= PRIORITY_INTERACTIVE,
+        "attempts": r["attempts"],
+        "maxAttempts": MAX_ATTEMPTS,
+        "error": r.get("error"),
+        "updatedAt": r.get("updated_at"),
+    } for r in rows[:limit]]
+
+
+def settings():
+    """What the consumer is configured to do, for the same screen."""
+    return {
+        "enabled": ENABLED,
+        "concurrency": MAX_CONCURRENT,
+        "gapSeconds": GAP_SECONDS,
+        "maxAttempts": MAX_ATTEMPTS,
+        "retryAfterSeconds": FAILED_RETRY_SECONDS,
+    }
+
+
+def retry_failed(user_id):
+    """Put every given-up job back in the queue, now, at the user's request.
+
+    The automatic retry waits out a cooldown so a flapping upstream is not
+    hammered; a person pressing 重试 has decided it is worth trying again.
+    """
+    execute(
+        "UPDATE ai_jobs SET status = 'pending', attempts = 0, error = NULL, "
+        "holder = NULL, claimed_at = NULL, updated_at = ? "
+        "WHERE user_id = ? AND status = 'failed'",
+        [_iso(_now()), user_id],
+    )
+    return pending_count(user_id)
+
+
 def pending_count(user_id=None):
     sql = "SELECT COUNT(*) AS n FROM ai_jobs WHERE status IN ('pending', 'running')"
     params = []