feat: add aggressive shrink option

[rvalyi]

Adds an --shrink-aggressive option to the CLI and a corresponding aggressive=True parameter to the shrink_python_file function.

When enabled, this option prevents writing method bodies ('pass') for shrunken Python files, retaining only class and field definitions.

Also adds a new test file for the shrinker functionality.

[codecov]

Codecov Report

❌ Patch coverage is 91.42857% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.15%. Comparing base (aeed0c0) to head (2c95a3e).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/akaidoo/shrinker.py	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #7      +/-   ##
==========================================
+ Coverage   64.81%   69.15%   +4.34%     
==========================================
  Files           4        5       +1     
  Lines         719      749      +30     
  Branches      137      138       +1     
==========================================
+ Hits          466      518      +52     
+ Misses        191      167      -24     
- Partials       62       64       +2     

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