Fix stuck light transitioning flag after task cancellation

[TheJulianJES]

DRAFT.

The Git diff is horrible to look at, but it's just try/finally being added in those parts and one small guard (59611bf).

AI summary

When a mode: restart automation fires while a light turn-on or turn-off is in progress, Home Assistant cancels the running asyncio task. If that cancellation lands between async_transition_set_flag() and async_transition_start_timer(), the _transitioning_individual flag is left True with no timer to clear it. The light then ignores all incoming attribute reports indefinitely.

• Wrap the body of async_turn_on and async_turn_off in try/finally blocks. The finally clause calls async_transition_complete() when the flag is stuck (set but no timer running), covering task cancellation and unexpected exceptions.
• As a side effect, a pre-existing bug is also fixed: when the second move_to_level call in the new_color_provided_while_off path failed, the code returned without calling async_transition_complete() or starting the transition timer — leaving the flag stuck.
  • An explicit guard is now added there, consistent with all other early-return error paths (59611bf).

[codecov]

Codecov Report

❌ Patch coverage is 72.64151% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.43%. Comparing base (aa03919) to head (59611bf).

Files with missing lines	Patch %	Lines
zha/application/platforms/light/__init__.py	72.64%	29 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #672      +/-   ##
==========================================
- Coverage   97.44%   97.43%   -0.02%     
==========================================
  Files          62       62              
  Lines       10731    10740       +9     
==========================================
+ Hits        10457    10464       +7     
- Misses        274      276       +2     

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