Add LottieFiles motion-design skill

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0119deVM65AKpJiLTLhEdDg9

.agents/skills/motion-design/reference/quality-checklist.md

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+# Quality Checklist
+
+## Visual Quality
+- [ ] Elements >40px for motion, >100px for detail
+- [ ] Readable at full speed without slow-motion
+- [ ] Clear primary, secondary, ambient layers
+- [ ] Counter-motion for balance where needed
+- [ ] Natural arcs (unless intentionally mechanical)
+- [ ] 1/3 rule (distance): no unbroken motion >1/3 container
+- [ ] 1/3 rule (density): max 1/3 elements active simultaneously
+
+## Technical Quality
+- [ ] No linear easing on spatial movement
+- [ ] Duration matches element type table
+- [ ] Ease-out entrances, ease-in exits
+- [ ] Duration proportional to distance
+- [ ] Entrance duration >= exit duration
+- [ ] Not opacity-only for important state changes
+- [ ] Stagger total <500ms
+- [ ] Follow-through: child elements offset 50-150ms
+
+## Emotional Quality
+- [ ] Target emotion identified before properties
+- [ ] Personality archetype matches brand
+- [ ] Setup → action → resolution structure
+- [ ] Intensity matches interaction importance
+- [ ] Consistent: same interaction = same motion
+- [ ] Appropriate on 100th viewing
+
+## Performance Quality
+- [ ] Primary motion uses transform + opacity
+- [ ] <20 animated elements per viewport
+- [ ] No layout-triggering properties animated
+- [ ] Elements staggered, not simultaneous
+- [ ] Maintains 60fps (30fps acceptable for ambient)
+
+## Accessibility Quality
+- [ ] prefers-reduced-motion alternative provided
+- [ ] No vestibular triggers without alternative
+- [ ] Same interaction = same animation
+- [ ] Critical info not motion-only
+- [ ] Animations >5s are pausable
+
+## Severity Tiers
+
+### CRITICAL
+- Linear easing on spatial movement
+- Opacity-only for important states
+- Exceeds 1/3 screen rule
+- Missing primary layer
+- Stagger >500ms
+- Layout property animation causing jank
+
+### HIGH
+- Missing secondary layer
+- Duration mismatch with element type
+- Wrong directional easing
+- Inconsistent personality
+- No follow-through
+- Missing reduced-motion alternative
+
+### MEDIUM
+- Missing ambient layer
+- No anticipation phase
+- Overshoot mismatch
+- Could use better arcs
+- Missing counter-motion