fix(scheduler): daily slot off-plan + cross-midnight resume (#8)

- Cross-midnight: unfinished yesterday seals ASAP with yesterday's stat_date;
  force seal ignores today's snapshot_at gate when stat_date < today.
- Off-plan already_completed: compare completion started_at (not finished_at)
  to today's planned slot; earlier → still run at slot for all daily tasks.
- Cold start: bootstrap task:state from task:last / seed markers.
- ensure_pending: do not glue new due onto a different day's unfinished state.
- run_if_needed(force): keep_scraped True for seal, False for CLI --force.
- Scheduler due_reader: pick up disk due_at each loop (seed→evening seal).

reaction_board/scheduler.py

@@ -59,6 +59,7 @@ class Scheduler:
         clock=time.time,
         sleeper=time.sleep,
         logger=None,
+        due_reader: Callable[[str], float | None] | None = None,
     ) -> None:
         if not tasks:
             raise ValueError("至少需要一个调度任务")
@@ -69,6 +70,8 @@ class Scheduler:
         self._clock = clock
         self._sleeper = sleeper
         self.logger = logger
+        # 每轮从落盘 due_at 刷新 next_run（seed 挂当晚 seal 等同进程可见）
+        self._due_reader = due_reader
 
     def _log(self, level: str, event: str, **fields) -> None:
         if self.logger is not None:
@@ -78,6 +81,10 @@ class Scheduler:
         current = self._clock() if now is None else now
         results: list[TaskResult] = []
         for task in self.tasks:
+            if self._due_reader is not None:
+                disk_due = self._due_reader(task.name)
+                if disk_due is not None:
+                    task.next_run = float(disk_due)
             if task.next_run > current:
                 continue
             started = current