Add index.ts barrel export and update file headers

[NEKOYASAN]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.70%. Comparing base (d1cc4f6) to head (33e268b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #6   +/-   ##
=======================================
  Coverage   93.70%   93.70%           
=======================================
  Files           5        5           
  Lines         302      302           
  Branches       94       94           
=======================================
  Hits          283      283           
  Misses          1        1           
  Partials       18       18           

Flag	Coverage Δ
generator	93.70% <100.00%> (ø)

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