fix: prevent deadlock when Actor.exit() is called from an event listener

[vdusek]

Actor.exit() / Actor.fail() called from within an event listener (e.g. an ABORTING handler cleaning up on a graceful abort) deadlocked into a RecursionError and never completed cleanup. The cleanup path waits for all tracked event-listener tasks to finish - including the listener task that called exit() - so it awaits its own await-chain; when that wait times out the cancellation recurses into itself. As a result Actor._active stayed True, the event and charging managers never shut down, state was never persisted, and sys.exit never ran - the run only died when force-killed.

The fix detaches the caller's own task from the event manager's listener-task set for the duration of cleanup and restores it afterwards (so its wrapper can still deregister it), so neither the direct wait nor the one inside the event-manager shutdown blocks on it. It's a no-op on the normal, non-listener exit path, and mirrors the workaround reboot() already uses for this same deadlock class.

The regression test registers an ABORTING listener that calls Actor.exit() and asserts the exit completes, the event manager shuts down, and no RecursionError is logged; it fails on the old code and passes with the fix.

✍️ Drafted by Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 88.88889% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.95%. Comparing base (58d6da1) to head (b2a2255).

Files with missing lines	Patch %	Lines
src/apify/_actor.py	88.88%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1061      +/-   ##
==========================================
+ Coverage   91.89%   91.95%   +0.06%     
==========================================
  Files          51       51              
  Lines        3232     3245      +13     
==========================================
+ Hits         2970     2984      +14     
+ Misses        262      261       -1     

Flag	Coverage Δ
e2e	35.28% <16.66%> (-0.05%)	⬇️
integration	57.22% <77.77%> (+0.14%)	⬆️
unit	83.32% <88.88%> (+0.06%)	⬆️

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[vdusek]

maybe we can close this in favor of apify/crawlee-python#2088