fix(review): add unconditional mark_dirty() in _apply_stale_dispatch

resolve_stale_running only calls mark_dirty() on the dead-dispatch path.
The reaper unconditionally mutates dispatch fields afterward (ended_at,
reaper_reason, reaper_dispatch_id, tombstone, reaper event), so
mark_dirty() must be called unconditionally to ensure persistence.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Trecek

src/autoskillit/fleet/_dispatch_reaper.py

@@ -71,6 +71,8 @@ def _apply_stale_dispatch(
 
     _append_reaper_event(dispatch, reason, reaper_dispatch_id)
 
+    m.mark_dirty()
+
 
 def _mark_dead_pid(
     dry_run: bool,