Add design-first workflow aligned with opencode boilerplate

- New commands: /define-design, /update-design, /generate-app (web | flutter | winui3)
- New skills: ui-design, design-tokens, platform-ui-generation
- /add-feature: check design spec before implementation (Step 3.5) and reconcile all six persistent docs after implementation (Step 8)
- /setup-project: automatic document creation with self-check checkpoints
- CLAUDE.md: document docs/design/, .claude/ configuration, and the design phase in the development process
- Enrich subagent descriptions; allowlist new skills in settings.json
- Add docs/design/README.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.claude/commands/setup-project.md

@@ -1,10 +1,10 @@
 ---
-description: "Initial setup: interactively create the six persistent documents"
+description: "Initial setup: automatically create the six persistent documents"
 ---
 
 # Initial Project Setup
 
-This command interactively creates the project's six persistent documents.
+This command automatically creates the project's six persistent documents without pausing for human feedback between steps.
 
 ## How to Run
 
@@ -26,7 +26,7 @@ ls docs/ideas/
 
 # If no files exist
 ⚠️  No files found in docs/ideas/
-   The PRD will be created interactively
+   The PRD will be created from the project context
 ```
 
 ## Procedure
@@ -38,21 +38,21 @@ ls docs/ideas/
 
 ### Step 1: Create the Product Requirements Document
 
-1. Load the **prd-writing skill**
+1. Load the **prd-writing skill** to guide PRD creation
 2. Create `docs/product-requirements.md` based on the contents of `docs/ideas/`
 3. Flesh out the ideas raised during brainstorming:
    - Detailed user stories
    - Acceptance criteria
    - Non-functional requirements
    - Success metrics
-4. Ask the user for confirmation and **wait until approved**
+4. Run the skill's self-check checkpoints; if issues are found, fix them inline, then proceed immediately to the next step
 
-**The subsequent steps are based on the Product Requirements Document, so they are created automatically**
+**All subsequent steps run automatically without waiting for human feedback.**
 
 ### Step 2: Create the Functional Design Document
 
 1. Load the **functional-design skill**
-1. Read `docs/product-requirements.md`
+2. Read `docs/product-requirements.md`
 3. Create `docs/functional-design.md` following the skill's template and guide
 
 ### Step 3: Create the Architecture Design Document