Screenshot baselines live here.

Bootstrap with:

    HM_SCREENSHOT_BOOTSTRAP=1 \
        uv run pytest tests/ui/_screenshot_diff/test_screenshots.py \
                      -m browser

then `cp` the produced `*__actual.png` files over the matching baseline
filenames after visual review.

Baselines are intentionally NOT auto-generated by CI — a human must
review each new baseline so the suite catches accidental palette drift.
