fix: exit already-entered contexts when Actor or event manager init fails

[vdusek]

Description

A failed __aenter__ never triggers __aexit__, so resources entered earlier inside __aenter__ must be unwound manually before re-raising. Two paths leaked this way:

• ApifyEventManager.__aenter__ raised on a websocket connection failure without exiting the already-entered parent EventManager, leaving its recurring persist-state task dangling.
• _ActorType.__aenter__ left the event manager entered when the charging manager's __aenter__ raised.

Both paths now exit the already-entered context before propagating the exception. except BaseException is used deliberately so that a CancelledError during charging manager init also unwinds the event manager.

Testing

• New regression test for the charging manager failure path (test_failed_charging_manager_init_does_not_leak_event_manager).
• Extended test_lifecycle_on_platform_without_websocket with assertions that the event manager is inactive and the persist-state task is stopped after the failure.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.87%. Comparing base (2cc5602) to head (4a0c09f).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #969      +/-   ##
==========================================
- Coverage   89.91%   89.87%   -0.05%     
==========================================
  Files          49       49              
  Lines        3085     3090       +5     
==========================================
+ Hits         2774     2777       +3     
- Misses        311      313       +2     

Flag	Coverage Δ
e2e	35.92% <0.00%> (-0.06%)	⬇️
integration	56.92% <33.33%> (-0.06%)	⬇️
unit	78.67% <100.00%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.