fix: handle TimeoutError in Actor __aexit__ to prevent resource leaks

[vdusek]

Summary

• When Actor cleanup exceeded _cleanup_timeout, the unhandled TimeoutError from asyncio.wait_for left the Actor in a broken state
• _is_initialized was never reset to False, event/charging managers could be left partially shut down, and sys.exit() was never called even when _exit_process was True
• Now the TimeoutError is caught, critical resource cleanup (event manager, charging manager) is forced even after timeout, and _is_initialized is always reset via a finally block

Test plan

• Verify existing tests pass
• Test Actor exit with a very short _cleanup_timeout and a slow event listener to confirm the timeout path logs a warning and still completes shutdown cleanly

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.86%. Comparing base (56aa42e) to head (ce4dfcf).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
src/apify/_actor.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #776      +/-   ##
==========================================
- Coverage   81.91%   81.86%   -0.06%     
==========================================
  Files          46       46              
  Lines        2693     2696       +3     
==========================================
+ Hits         2206     2207       +1     
- Misses        487      489       +2     

Flag	Coverage Δ
integration	55.93% <60.00%> (-0.03%)	⬇️
unit	68.02% <60.00%> (-0.04%)	⬇️

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