docs: merge UX patterns into design-philosophy, delete ux-patterns.md

- Add Accessibility Baseline section with WCAG 2.1 AA requirements
- Add Quality Checklist for shipping verification
- Delete standalone ux-patterns.md (all useful content merged)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/research/design-philosophy.md

@@ -142,6 +142,78 @@ Research from Baymard Institute (200,000+ hours of UX testing):
 - **F-pattern** (product pages): Horizontal top, shorter line below, vertical down left
 - **Z-pattern** (landing pages): Top-left → top-right → diagonal → bottom-right
 
+## Accessibility Baseline
+
+Every theme must meet WCAG 2.1 AA:
+
+### Colour Contrast
+- Normal text: 4.5:1 minimum
+- Large text (18px+ or 14px bold): 3:1 minimum
+- UI components and graphics: 3:1 minimum
+
+### Focus Indicators
+- Visible focus ring on all interactive elements
+- Never remove outline without replacement
+- Ring should have 3:1 contrast with adjacent colours
+
+### Touch Targets
+- Minimum 44×44px for touch targets
+- 8px minimum spacing between targets
+
+### Screen Reader Support
+- Semantic HTML (button for buttons, not div)
+- Alt text on all images
+- ARIA labels where needed
+- Skip links for keyboard navigation
+- Logical heading hierarchy (h1 → h2 → h3)
+
+## Quality Checklist
+
+Before shipping, verify:
+
+### Layout
+- [ ] Mobile-first responsive design
+- [ ] No horizontal scroll on any viewport
+- [ ] Content readable at 320px minimum
+- [ ] Touch targets 44×44px minimum
+
+### Navigation
+- [ ] Logo links to homepage
+- [ ] Cart always accessible
+- [ ] Current page indicated
+- [ ] Mobile menu works smoothly
+
+### Product Cards
+- [ ] Consistent aspect ratios
+- [ ] Price clearly visible
+- [ ] Hover state provides value
+- [ ] Links are obvious
+
+### Product Page
+- [ ] Images zoomable
+- [ ] Price prominent
+- [ ] Add to Cart visible on mobile
+- [ ] Trust signals visible
+
+### Ethical Design
+- [ ] No fake urgency/scarcity
+- [ ] No confirmshaming
+- [ ] No hidden costs
+- [ ] Clear, neutral options
+- [ ] Honest product information
+
+### Accessibility
+- [ ] Colour contrast passes WCAG AA
+- [ ] Focus rings visible
+- [ ] Semantic HTML
+- [ ] Alt text on images
+- [ ] Keyboard navigable
+
+### Performance
+- [ ] Images lazy loaded (except hero)
+- [ ] Fonts preloaded
+- [ ] No layout shift
+
 ## Combination Count
 
 With current options, the system offers: