feat: add ui_design_specialist (Phase 3 UI Design) v0.2.0

- New specialist: ui_design_specialist with iterative mockup dialog
- New Phase 3 (UI Design) between Architecture and Implementation
- Relay model: orchestrator passes responses verbatim in Phase 3
- Cost-control exception for UI Design phase (unlimited subagent calls)
- Webspace mockup workflow with cache-buster and obscure dirs
- UX states coverage (loading, empty, error, partial)
- WCAG 2.1 AA accessibility guidelines
- Design tokens (CSS custom properties) in design system
- Component states (hover, focus, active, disabled, loading, error)
- Sitemap/wireframe before mockups for complex UIs
- Real content strategy (no Lorem Ipsum)
- Form validation UX in mockups
- Dark mode and i18n support (optional)
- Design handoff support (specialist available during implementation)
- Skip mechanism for non-UI projects
- Mockup state file for context compression recovery
- Multi-page mockup strategy with index.html
- task_graph.json mockup references
- Plugin version: 0.1.14 -> 0.2.0
- 47 files changed across 7 implementation blocks
- 3 review rounds with 41 corrections integrated

help/handover/help.md

@@ -48,7 +48,7 @@ handover_to_specialist(
 
 | Argument | Required | Notes |
 |----------|----------|-------|
-| `specialist_profile` | ✅ | One of the 11 known profiles (see below). |
+| `specialist_profile` | ✅ | One of the 12 known profiles (see below). |
 | `topic` | ✅ | Short slug. Used in the briefing filename. |
 | `summary` | recommended | LLM-curated; max 300 tokens recommended. |
 | `recent_turns` | optional | Auto-trimmed to `include_recent_turns`. |
@@ -77,11 +77,11 @@ allow-list (defence-in-depth): a typo in the profile name produces a clear
 - `runtime_devops_engineer`
 - `security_data_engineer`
 - `solution_architect`
+- `ui_design_specialist`
 - `test_debug_engineer`
 - `hacker`
 
-`frontend_designer` is **not** a known profile in Phase 1. It is on the
-roadmap for Phase 2.
+`frontend_designer` is **not** a known profile. Use `ui_design_specialist` instead for UI design tasks.
 
 ---