eslint.config.mjs does not ignore .claude/, so anything kept there fails `npm run lint` with parser-project errors

[latekvo]

What happens

npm run lint reports errors for files under .claude/, a directory that is git-ignored (.gitignore:54) and holds no project sources.

Every TypeScript file found there fails with a parsing error, because nothing under .claude/ belongs to any tsconfig referenced by parserOptions.project:

0:0  error  Parsing error: "parserOptions.project" has been provided for @typescript-eslint/parser.
The file was not found in any of the provided project(s): .claude/<path>

Why

ESLint's flat config does not read .gitignore. It honours only its own ignores array, and the array in eslint.config.mjs (lines 11-28) does not list .claude/.

The comment directly above that array states it "Mirrors the ignores in .prettierignore + .gitignore". Since .gitignore contains .claude/, the array does not currently match its own stated intent.

Prettier is not affected and needs no change: since 3.0 its default --ignore-path includes .gitignore, so it already skips the directory. Verified on 3.8.5 — a whole-repo prettier --check . passes over a badly formatted file under .claude/, and flags it only when forced with --ignore-path .prettierignore.

Reproduction

mkdir -p .claude/scratch
printf 'const   unusedVar:any=1\n' > .claude/scratch/bad.ts
npx eslint .          # .claude/scratch/bad.ts is reported
rm -rf .claude/scratch

Impact

.claude/worktrees/ is a natural place to keep git worktrees, and each worktree is a complete copy of the repo. On a checkout with three worktrees there, npm run lint reported 1008 errors, all of them from those copies and none from argent's own sources. npm run lint runs with --max-warnings 0, so the local lint gate fails and the real output is buried.

CI is unaffected: .claude/ is not tracked, so a fresh checkout never contains it. This is a local developer-experience problem only.

Suggested fix

Add ".claude/" to the ignores array in eslint.config.mjs.