fix(coordinator): guarantee setup event is set to prevent deadlock on failed initialization

[firstof9]

Summary

This PR resolves #668.

When the Keymaster coordinator fails to set up (due to connection failures or missing dependencies during Home Assistant startup), the _initial_setup_done_event is never set. Consequently, when a user tries to delete or reconfigure the integration entry afterwards, any downstream calls waiting on this event (await self._initial_setup_done_event.wait()) hang indefinitely. This blocks the config entry unloading task, causing Home Assistant Core to hang and eventually be terminated by the watchdog (SIGKILL / Exit 256).

Proposed change

Wrapping the core setup in a try...finally block ensures that _initial_setup_done_event is always set even if setup fails, allowing entry cleanup/deletion or reload to proceed normally.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes ISSUE: Home Assistant Core crashes when reconfiguring or deleting Keymaster integration entry #668
• This PR is related to issue:

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.23%. Comparing base (cdb4922) to head (e4b8c3a).
⚠️ Report is 186 commits behind head on main.
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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #669      +/-   ##
==========================================
+ Coverage   84.14%   92.23%   +8.09%     
==========================================
  Files          10       41      +31     
  Lines         801     4817    +4016     
  Branches        0       30      +30     
==========================================
+ Hits          674     4443    +3769     
- Misses        127      374     +247     

Flag	Coverage Δ
python	92.09% <100.00%> (?)

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