Fix missing __init__.py in intermediate package directories

[koxudaxi]

Summary

• Fix issue where __init__.py files were not generated for intermediate directories when creating nested package structures from dot-separated schema names (e.g., io.example.api.v1.Resolution)
• Handle both single-level and multi-level modules correctly

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.66%. Comparing base (747fed5) to head (4d4148b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2662   +/-   ##
=======================================
  Coverage   99.66%   99.66%           
=======================================
  Files          76       76           
  Lines       10481    10486    +5     
  Branches     1261     1264    +3     
=======================================
+ Hits        10446    10451    +5     
  Misses         16       16           
  Partials       19       19           

Flag	Coverage Δ
unittests	99.66% <100.00%> (+<0.01%)	⬆️

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[codspeed-hq]

CodSpeed Performance Report

Merging #2662 will not alter performance

_{Comparing fix/missing-init-py-intermediate-packages (4d4148b) with main (747fed5)}

Summary

✅ 50 untouched
⏩ 3 skipped¹

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩