chore: move lengthy source code comments to API.md

[bartveneman]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.66%. Comparing base (02571e2) to head (2a490fb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #84   +/-   ##
=======================================
  Coverage   94.66%   94.66%           
=======================================
  Files          15       15           
  Lines        2362     2362           
  Branches      590      590           
=======================================
  Hits         2236     2236           
  Misses        126      126           

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[codecov-commenter]

Bundle Report

Changes will decrease total bundle size by 413 bytes (-0.32%) ⬇️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	126.92kB	-413 bytes (-0.32%) ⬇️

Affected Assets, Files, and Routes:

view changes for bundle: @projectwallace/css-parser-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
css-*.js	-413 bytes	16.37kB	-2.46%

Files in css-*.js:

• ./src/css-node.ts → Total Size: 15.57kB