Add aitells-action to Linting — scan PR text for AI fingerprints

[Perufitlife]

Adds Perufitlife/aitells-action to the Linting section, near alex-action which catches inconsiderate writing.

What it does: scans PR title, body, and commit messages for the 12 most reliable AI fingerprints (em-dashes, "delve", parallel bullets, "navigate the X", "in conclusion", and 8 more). Posts a friendly summary comment on every PR with a humanness score 0-100.

- uses: Perufitlife/aitells-action@v1
  with:
    target: both        # pr_body | commits | both
    fail-on: 65         # block merge if humanness < 65
    comment: true

Free, no API key. Built after my own Reddit account got publicly called out twice in 24h for "all comments AI generated". Companion to aitells.vercel.app (web app).