fix(events): prevent deadlock when closing or waiting for listeners from within a listener

[vdusek]

Calling EventManager.wait_for_all_listeners_to_complete() - or closing the manager via __aexit__ - from within an event listener deadlocked. The listener runs in a task that is itself registered in _listener_tasks, so the asyncio.gather(...) inside the wait ends up awaiting the very task that is awaiting it. Under a close timeout this self-await cycle degrades further into a RecursionError.

The fix is two small changes in EventManager:

• wait_for_all_listeners_to_complete() now excludes asyncio.current_task() from the gathered set, so a listener never waits on its own completion.
• The listener wrapper's finally uses set.discard() instead of set.remove(), since __aexit__ may have already cleared the task set while the listener was mid-flight (avoids a spurious KeyError).

Both are no-ops for the normal case (a non-listener caller waiting for listeners). Added regression tests covering waiting for all listeners from within a listener, and closing the manager from within a listener.

This unblocks apify/apify-sdk-python#1061, where Actor.exit() is called from inside an event listener (e.g. an ABORTING handler) - with this fix the SDK can drop its _detach_current_listener_task workaround.

✍️ Drafted by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.46%. Comparing base (2bc10ad) to head (c5405e2).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2088      +/-   ##
==========================================
- Coverage   93.47%   93.46%   -0.02%     
==========================================
  Files         181      181              
  Lines       12552    12560       +8     
==========================================
+ Hits        11733    11739       +6     
- Misses        819      821       +2     

Flag	Coverage Δ
unit	93.46% <100.00%> (-0.02%)	⬇️

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