feat(p0): add favorite folder sync and sqlite data foundation

Implement P0 of the reaction dashboard: config loading with hot reload, SQLite migrations with backups, single-writer queue, read-only Bilibili fav client, folder import/diff sync, invalid-resource handling, blacklist seed, scheduler, and JSON redacted logging. Includes offline unit and transport-level contract tests; all existing and new tests pass.

reaction_board/scheduler.py

@@ -0,0 +1,115 @@
+# -*- coding: utf-8 -*-
+"""单进程内置调度器。
+
+P0 只注册收藏夹同步任务；P1/P3 会在同一调度器上追加快照、粉丝和发现任务。
+调度只负责“什么时候运行”，具体任务保持幂等，并在自己的服务层处理重试。
+"""
+
+from __future__ import annotations
+
+import time
+from dataclasses import dataclass
+from typing import Any, Callable, Sequence
+
+
+@dataclass
+class ScheduledTask:
+    name: str
+    interval: float
+    fn: Callable[[], Any]
+    next_run: float = 0.0
+
+
+@dataclass
+class TaskResult:
+    name: str
+    started_at: float
+    finished_at: float
+    ok: bool
+    error: str | None = None
+
+    def as_dict(self) -> dict[str, Any]:
+        return {
+            "name": self.name,
+            "started_at": int(self.started_at),
+            "finished_at": int(self.finished_at),
+            "ok": self.ok,
+            "error": self.error,
+        }
+
+
+class Scheduler:
+    def __init__(
+        self,
+        tasks: Sequence[ScheduledTask],
+        *,
+        clock=time.time,
+        sleeper=time.sleep,
+        logger=None,
+    ) -> None:
+        if not tasks:
+            raise ValueError("至少需要一个调度任务")
+        for task in tasks:
+            if task.interval <= 0:
+                raise ValueError(f"任务 {task.name} 的 interval 必须大于 0")
+        self.tasks = list(tasks)
+        self._clock = clock
+        self._sleeper = sleeper
+        self.logger = logger
+
+    def _log(self, level: str, event: str, **fields) -> None:
+        if self.logger is not None:
+            getattr(self.logger, level)(event, **fields)
+
+    def run_due(self, *, now: float | None = None) -> list[TaskResult]:
+        current = self._clock() if now is None else now
+        results: list[TaskResult] = []
+        for task in self.tasks:
+            if task.next_run > current:
+                continue
+            started = current
+            error: str | None = None
+            try:
+                task.fn()
+            except Exception as exc:  # noqa: BLE001  单任务失败不终止调度
+                error = str(exc)
+                self._log("error", "scheduler.task_error", task=task.name, error=error)
+            else:
+                self._log("info", "scheduler.task_ok", task=task.name)
+            finished = self._clock()
+            task.next_run = started + task.interval
+            result = TaskResult(
+                name=task.name,
+                started_at=started,
+                finished_at=finished,
+                ok=error is None,
+                error=error,
+            )
+            results.append(result)
+        return results
+
+    def run_forever(
+        self,
+        *,
+        stop_event=None,
+        poll_seconds: float = 30.0,
+        max_iterations: int | None = None,
+    ) -> list[TaskResult]:
+        """阻塞运行；``stop_event`` 或 ``max_iterations`` 用于可控退出/测试。"""
+        if poll_seconds <= 0:
+            raise ValueError("poll_seconds 必须大于 0")
+        all_results: list[TaskResult] = []
+        iterations = 0
+        while True:
+            if stop_event is not None and stop_event.is_set():
+                break
+            all_results.extend(self.run_due())
+            iterations += 1
+            if max_iterations is not None and iterations >= max_iterations:
+                break
+            if stop_event is not None:
+                if stop_event.wait(poll_seconds):
+                    break
+            else:
+                self._sleeper(poll_seconds)
+        return all_results