Refactor and Clean up the Lisp type and Add a New Scheme Type

[jgarte]

See the below closed PR for more information on what is being requested.

#3254

Lisp (Common Lisp, etc.) and Scheme are two different programming languages.

We should have better granularity and separation when grepping for files in Common Lisp code bases versus Scheme codebases.

[jgarte]

@BurntSushi Hi, what do you think of distinguishing scheme and lisp file types when using the -t flag? All best.

[oaksprout]

Would you want this one done? — Splitting the Lisp file-type detection into separate Lisp and Scheme types so Scheme files aren't mislabeled. If yes, we'll do it and open a PR; if not, say so (or just ignore this) and we won't touch it.

How it works: an AI agent does the work against your write-up; it's independently checked in a clean container (your test suite, network off) before anything reaches you; a human reviews it, submits it, and answers the review. You keep full control — nothing lands unless you merge it.

Recent examples of the same flow on other projects: stretchr/testify#1932, pypa/pip-audit#1089, strawberry-graphql/strawberry#4555.

We're testing whether work offered this way is useful to maintainers — a blunt "no" is as helpful as a yes.