chore: migrate away from kcd-scripts

[TrevorBurnham]

Fixes #696

What:

This CR implements a testing and linting configuration for this project that replaces kcd-scripts.

The only intended difference in behavior is that the tests no longer run as part of the precommit hook. Due to the bug described at #696, the --findRelatedTests approach used in kcd-scripts for running the minimal set of tests isn't viable.

All non-config code diffs are autofixes from running the linter and formatter.

Why:

Per kentcdodds/kcd-scripts#245 (comment), @kentcdodds recommends migrating away from kcd-scripts. It's not actively maintained and has known bugs.

How:

I used Claude Sonnet 4.5 to assist. The LLM was instructed to set up a configuration with minimal changes relative to kcd-scripts. I did update some dev dependencies (most notably eslint and typescript-eslint) due to peer dependency conflicts between kcd-scripts' versions of those dependencies and the project's existing TypeScript version.

I've confirmed that all tests pass and that the pre-commit hook works as intended.

Checklist:

• Documentation - N/A
• Tests - N/A
• Updated Type Definitions - N/A
• Ready to be merged