refactor: order declarations by reach as declscope 0.20.4 refines it

[mpyw]

Summary

Under the type-unit rule from #189, boolSetting and its UnmarshalYAML method in internal/config/config.go are one unit. So the exported File type now comes before that unit. This PR only moves File. No behavior changes.

Verification

• mise x -- ./test_all.sh passes. The spec stage was skipped locally because fslc was not on PATH.
• The throwaway ordering checker, updated for type units and section comments, reports nothing.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.02%. Comparing base (7593f14) to head (c4972f4).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #190   +/-   ##
=======================================
  Coverage   99.02%   99.02%           
=======================================
  Files          50       50           
  Lines        4214     4214           
=======================================
  Hits         4173     4173           
  Misses         41       41           

Flag	Coverage Δ
unittests	99.02% <100.00%> (ø)

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