fix: back off scheduler lock retries

src/wf_scheduling/lifecycle.py

@@ -516,7 +516,10 @@ class SchedulerService:
         cancelled = False
         while not self._lock.acquire(blocking=False):
             try:
-                await asyncio.sleep(0)
+                # The poll worker may hold this lock during file I/O. A
+                # nonzero delay avoids busy-spinning the event loop while
+                # still allowing registration and stop callbacks to run.
+                await asyncio.sleep(0.001)
             except asyncio.CancelledError:
                 if not continue_after_cancel:
                     raise