feat: enhance StaticSettings to ensure directory creation and add platformdirs dependency

[EspenAlbert]

No description provided.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.51%. Comparing base (34a2717) to head (ac43e0e).

Files with missing lines	Patch %	Lines
model_lib/static_settings.py	90.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #4      +/-   ##
==========================================
+ Coverage   80.41%   80.51%   +0.09%     
==========================================
  Files          26       26              
  Lines        1108     1129      +21     
==========================================
+ Hits          891      909      +18     
- Misses        217      220       +3     

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