refactor: Use Optional for InitVar type hint

[ruoyeruolan]

Update type hint from InitVar[list[str]] to InitVar[Optional[list[str]]] to explicitly allow None during initialization, matching the default value and improving type checker accuracy

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.86%. Comparing base (cdd8032) to head (d54cac4).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #21943   +/-   ##
=======================================
  Coverage   80.86%   80.86%           
=======================================
  Files        1631     1631           
  Lines      235490   235490           
  Branches     2693     2693           
=======================================
+ Hits       190438   190440    +2     
+ Misses      44419    44416    -3     
- Partials      633      634    +1     

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