refactor: update grammar models

[tigarmo]

"GrammarStr" becomes "Grammar[str]", and so on.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.58%. Comparing base (6ff73a1) to head (d25b0c4).
Report is 37 commits behind head on main.

❗ Current head d25b0c4 differs from pull request most recent head 862ce34. Consider uploading reports for the commit 862ce34 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4746      +/-   ##
==========================================
+ Coverage   89.54%   89.58%   +0.04%     
==========================================
  Files         337      332       -5     
  Lines       22638    22104     -534     
==========================================
- Hits        20271    19802     -469     
+ Misses       2367     2302      -65     

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