feat: integrate animation token system into UI workflow

Fixes critical P0 issue where animation-tokens.json wasn't consumed by the
generate command, breaking the value chain. The animation extraction system
now properly flows through: animation-extract → tokens → generate → prototypes.

Changes:
- Added animation-extract command with hybrid CSS extraction + interactive
  fallback strategy
- Updated generate.md to load and inject animation tokens into prototypes
- Added CSS animation support (custom properties, keyframes, interactions,
  accessibility)
- Integrated animation extraction into explore-auto and imitate-auto workflows

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.claude/commands/workflow/ui-design/imitate-auto.md

@@ -20,9 +20,10 @@ allowed-tools: SlashCommand(*), TodoWrite(*), Read(*), Write(*), Bash(*)
 2. Phase 0: Initialize and parse parameters
 3. Phase 1: Screenshot capture (batch or deep mode) → **WAIT for completion** → Auto-continues
 4. Phase 2: Style extraction (complete design systems) → **WAIT for completion** → Auto-continues
-5. Phase 2.5: Layout extraction (structure templates) → **WAIT for completion** → Auto-continues
-6. Phase 3: Batch UI assembly → **WAIT for completion** → Auto-continues
-7. Phase 4: Design system integration → Reports completion
+5. Phase 2.3: Animation extraction (CSS auto mode) → **WAIT for completion** → Auto-continues
+6. Phase 2.5: Layout extraction (structure templates) → **WAIT for completion** → Auto-continues
+7. Phase 3: Batch UI assembly → **WAIT for completion** → Auto-continues
+8. Phase 4: Design system integration → Reports completion
 
 **Phase Transition Mechanism**:
 - `SlashCommand` is BLOCKING - execution pauses until completion