Fix nested hint naming for multi-level declarations

[MooVC]

Summary

• preserve nested type hint naming order when concatenating parent scopes
• add multi-level nested declaration snippets with expectations for all generation strategies
• align generator tests with updated expectation ordering

Testing

• PATH=$HOME/.dotnet:$PATH DOTNET_ROOT=$HOME/.dotnet dotnet test

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Codex Task

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.05%. Comparing base (5e1e8ab) to head (6e6159e).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #50      +/-   ##
==========================================
+ Coverage   90.28%   94.05%   +3.77%     
==========================================
  Files          60       60              
  Lines        1400     1397       -3     
  Branches      170      171       +1     
==========================================
+ Hits         1264     1314      +50     
  Misses         76       76              
+ Partials       60        7      -53     

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