Add UI/Frontend standards template (standards/ui-standards.md)

[nakurian]

Problem

The standards/ directory has coding-standards.md (backend-focused) and api-design.md (REST API), but nothing for frontend/UI services. When the builder agent creates a UI service, it has no guidance on:

• Component architecture (atomic design, feature-based, etc.)
• State management patterns (when to use global vs local state)
• Styling approach (CSS modules, Tailwind, styled-components, design tokens)
• Accessibility standards (WCAG level, ARIA requirements)
• Performance budgets (bundle size limits, LCP/FID/CLS targets)
• Responsive design breakpoints and approach
• Folder structure for frontend projects
• Form handling and validation patterns
• Error/loading/empty state UX patterns
• Internationalization (i18n) approach
• Image optimization strategy
• SEO requirements (meta tags, structured data, SSR/SSG decisions)
• Browser support matrix
• Design system / component library conventions

Proposed solution

Add standards/ui-standards.md as a default template covering:

# UI/Frontend Standards

## Component Architecture
- Component naming and organization
- When to split components
- Props vs context vs global state

## Styling
- Approach (Tailwind / CSS Modules / styled-components)
- Design tokens (colors, spacing, typography)
- Responsive breakpoints

## Accessibility
- WCAG 2.1 AA minimum
- Required ARIA attributes
- Keyboard navigation requirements
- Screen reader testing

## Performance
- Bundle size budget (e.g., < 200KB initial JS)
- Core Web Vitals targets (LCP < 2.5s, FID < 100ms, CLS < 0.1)
- Image optimization (WebP/AVIF, lazy loading)
- Code splitting strategy

## UX Patterns
- Loading states (skeleton screens vs spinners)
- Error states (inline vs toast vs page-level)
- Empty states
- Form validation (inline, on blur, on submit)
- Optimistic updates

## Testing
- Component testing (React Testing Library / Vue Test Utils)
- Visual regression (Chromatic / Percy)
- E2E critical paths (Playwright / Cypress)
- Accessibility testing (axe-core)

## SEO & Meta
- Required meta tags per page
- OpenGraph / Twitter cards
- Structured data (JSON-LD)
- SSR vs SSG decisions

Phase 0 setup should ask about UI preferences and generate this file accordingly. The spec agent (Phase 3) should read this when generating UI service specs.