采集任务支持手动触发 + 定时调度(cron)

后端:
- 新增 Scheduler + ScheduledTask 核心模块(croniter 解析 cron 表达式)
- 新增 Schedule 数据模型(alembic 0016)
- 新增 /api/v1/admin/schedules CRUD 接口
- lifespan 启动时注册默认定时任务并加载数据库配置
- 默认任务:每日比赛/积分榜/30分钟统计回填(默认禁用)

前端:
- 设置页新增「定时任务」管理区块
- 支持:新建/启用禁用/立即执行/删除定时任务
- 显示:任务ID、类型、cron表达式、上次执行时间/状态

依赖:新增 croniter>=2.0

Co-Authored-By: new-provider/LongCat-2.0 <<EMAIL>>

src/core/scheduler.py

@@ -0,0 +1,112 @@
+"""定时任务调度器:支持 cron 表达式触发采集任务。"""
+from __future__ import annotations
+
+import asyncio
+import logging
+from datetime import datetime, timedelta
+from typing import Callable, Coroutine
+
+from croniter import croniter
+
+logger = logging.getLogger(__name__)
+
+
+class ScheduledTask:
+    """一个定时任务。"""
+
+    def __init__(
+        self,
+        task_id: str,
+        cron: str,
+        fn: Callable[[], Coroutine],
+        enabled: bool = True,
+    ) -> None:
+        self.task_id = task_id
+        self.cron = cron
+        self.fn = fn
+        self.enabled = enabled
+        self.last_run: datetime | None = None
+        self.next_run: datetime | None = None
+        self._task: asyncio.Task | None = None
+        self._calc_next()
+
+    def _calc_next(self) -> None:
+        try:
+            self.next_run = croniter(self.cron, datetime.now).get_next(datetime)
+        except Exception:
+            self.next_run = None
+
+    def update(self, cron: str | None = None, enabled: bool | None = None) -> None:
+        if cron is not None:
+            self.cron = cron
+        if enabled is not None:
+            self.enabled = enabled
+        self._calc_next()
+
+    async def _run_loop(self) -> None:
+        while True:
+            if not self.enabled or not self.next_run:
+                await asyncio.sleep(60)
+                self._calc_next()
+                continue
+
+            now = datetime.now()
+            wait_seconds = (self.next_run - now).total_seconds()
+            if wait_seconds > 0:
+                await asyncio.sleep(min(wait_seconds, 60))
+                continue
+
+            # 执行任务
+            self.last_run = datetime.now()
+            self._calc_next()
+            try:
+                logger.info("定时任务触发: %s (cron=%s)", self.task_id, self.cron)
+                await self.fn()
+                logger.info("定时任务完成: %s", self.task_id)
+            except Exception:
+                logger.exception("定时任务失败: %s", self.task_id)
+
+
+class Scheduler:
+    """全局定时任务调度器。"""
+
+    def __init__(self) -> None:
+        self._tasks: dict[str, ScheduledTask] = {}
+
+    def register(
+        self,
+        task_id: str,
+        cron: str,
+        fn: Callable[[], Coroutine],
+        enabled: bool = True,
+    ) -> ScheduledTask:
+        if task_id in self._tasks:
+            self._tasks[task_id].update(cron=cron, enabled=enabled)
+            return self._tasks[task_id]
+        task = ScheduledTask(task_id, cron, fn, enabled)
+        self._tasks[task_id] = task
+        return task
+
+    def get(self, task_id: str) -> ScheduledTask | None:
+        return self._tasks.get(task_id)
+
+    def list_all(self) -> list[ScheduledTask]:
+        return list(self._tasks.values())
+
+    def remove(self, task_id: str) -> None:
+        self._tasks.pop(task_id, None)
+
+    async def start(self) -> None:
+        for task in self._tasks.values():
+            task._task = asyncio.create_task(task._run_loop())
+        logger.info("定时调度器已启动, 共 %d 个任务", len(self._tasks))
+
+    async def stop(self) -> None:
+        for task in self._tasks.values():
+            if task._task:
+                task._task.cancel()
+        self._tasks.clear()
+
+
+# 全局单例
+scheduler = Scheduler()