Remove vestigial ESLint config dependencies

[tbroadley]

Problem

yarn install printed two peer-dependency warnings:

warning " > eslint-config-airbnb-base@15.0.0" has incorrect peer dependency "eslint@^7.32.0 || ^8.2.0".
warning " > eslint-plugin-import@2.32.0" has incorrect peer dependency "eslint@^2 || ... || ^9".

What was vestigial vs. used

Both packages are vestigial. They were only ever referenced by .eslintrc.yml (extends: airbnb-base, plugin:import/typescript, and the import/* rules). The repo has since moved to a flat config, and eslint.config.js does not reference either package — it composes @eslint/js recommended, @typescript-eslint recommended, and a handful of custom rules. ESLint 10 no longer reads eslintrc files at all, so .eslintrc.yml was dead config and is removed here too.

Why not upgrade instead

No published release of either package supports ESLint 10:

• eslint-config-airbnb-base — latest is 15.0.0, peer range eslint@^7.32.0 || ^8.2.0
• eslint-plugin-import — latest is 2.32.0, peer range tops out at eslint@^9

Since the flat config never loaded them, removing them costs zero rule coverage.

Changes

• Remove eslint-config-airbnb-base and eslint-plugin-import from devDependencies
• Delete the stale .eslintrc.yml
• Drop the now-dangling .eslintrc.yml reference from a comment in eslint.config.js
• Add a ## [Unreleased] CHANGELOG entry

Verification

• yarn install — clean, no peer-dependency warnings
• yarn ci — spellcheck clean, lint clean, 101 mocha tests passing
• Sanity-checked that lint still reports real problems: a scratch .ts file with unused vars and an undefined identifier was flagged by @typescript-eslint/no-unused-vars and no-undef, then removed. The config is not silently linting nothing.

🤖 Generated with Claude Code