This follows the user's rulings: CI should not care which bash or which
standard utilities it runs, and jobs take what the ci dev shell provides.
- checkers.sh: remove find_modern_bash, the 5.1 floor (improvise-fd0j) and
exit 3. Suites run under $BASH with PATH unchanged.
- checkers-test.sh: remove sections 2, 5 and 5b (the fake bashes and utilbin).
They existed only to pin the floor.
- scripts/kb: drop the BSD `stat -f` fallback. kb needs the dev shell for tpl,
and that shell's stat is GNU.
- ci.yml: remove every `shell: bash` override, so every step runs in the dev
shell. Remove the web-toolchain version probe and the Playwright
version/browser probe. The shell's PLAYWRIGHT_BROWSERS_PATH pins the
browsers. npm ci stays because @playwright/test is not nix-provided.
- flake.nix: update the comments that promised those CI checks.
Reasoning: context/code/tooling.md section 5. Evidence:
context/test-evidence/tooling.md.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze
Edward Langley
754add31e2