feat: the heart monitor's beat follows how hurt someone is, not just …

[over2take]

…its color

The monitor's color always changed with health; now its rhythm does too, on the same thresholds: steady over half, twice as fast at half or less, fast, uneven and weakening at a quarter or less, then the flatline. Still no numbers, in the HEALTH folder and on the stream overlay alike, which now share one band rather than two copies of the thresholds. With reduced motion the trace holds still but keeps its shape, and a screen reader hears how it looks.

The steady beat is the trace the monitor has always drawn.

Summary

Test plan

• Tested locally
• Tests pass

Pre-merge checklist

Code quality:

• Code follows project style
• No breaking changes (or clearly documented)
• No console errors or warnings

Version & Release:

• Version bumped? If releasing to users, update:
  • frontend/package.json version
  • docker-compose.yml APP_VERSION
  • CHANGELOG.md with release notes
• GitHub Actions will auto-tag Docker images with the new version

Before merging to main:

• All tests passing
• PR reviewed and approved
• Branch is up to date with main
• No merge conflicts

Related issues