Restore rotateAnim loop behavior and keep reverse semantics

[tracygardner]

Summary

• restored rotateAnim loop behavior so loop: true spins continuously forward again
• kept reverse: true behavior as a forward-then-return animation
• ensured reverse: true + loop: true runs as repeated animate-then-reverse
• added an animation test that verifies reverse returns to the starting rotation

Implementation details

• api/animate.js
  • loop mode selection now distinguishes reverse (YOYO) from non-reverse loop (CYCLE)
  • keyframe construction now depends on whether this is a looping spin vs a one-shot reverse
  • animation end frame now uses double duration only for one-shot reverse
  • final rotation assignment on completion now restores start rotation for reverse mode
• tests/animate.test.js
  • added coverage for rotateAnim(..., { reverse: true }) ensuring it returns to initial orientation

Validation

• attempted to run: npm run test:api animate
• blocked by missing Playwright browser binary in environment
• attempted install: npx playwright install chromium
• blocked by upstream CDN 403 responses in this environment

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Codex Task