Add workflow infrastructure — ESLint, Prettier, Husky, Vitest, 7 new skills

Phase 1: Session log archived (1096→91 lines), D031 token access convention
Phase 2: ESLint v9 + Prettier + jsx-a11y, initial config and lint fixes
Phase 3: 7 new skills (polish, harden, normalize, clarify, typeset, quieter, adapt)
         + Vercel reference docs, updated audit/review-component refs
Phase 4: Husky + lint-staged pre-commit hooks, preflight updated to 8 checks
Phase 5: Vitest + Testing Library + /write-tests skill

- Badge.tsx colour maps unified to CSS variables (D031)
- 5 empty interface→type alias fixes (Switch, Radio, Divider, IconButton, Link)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/conventions/component-conventions.md

@@ -95,7 +95,9 @@ export default Button;
 
 ### Theming
 - **NEVER hardcode** colour values, spacing, font sizes, shadows, or border radii
-- Use `theme.palette.*`, `theme.spacing()`, `theme.typography.*`, `theme.shape.*`
+- **Semantic tokens** (text, surface, border, interactive, feedback, typography, spacing): use MUI theme accessors — `theme.palette.*`, `theme.spacing()`, `theme.typography.*`, `theme.shape.*` — when inside a theme callback. CSS variables (`var(--fa-color-*)`, `var(--fa-spacing-*)`) are also acceptable for semantic tokens when more ergonomic (e.g., static colour maps, non-callback contexts).
+- **Component tokens** (badge sizes, card shadows, input dimensions, etc.): use CSS variables (`var(--fa-badge-*)`, `var(--fa-card-*)`) — these are NOT mapped into the MUI theme.
+- See decision D031 in `docs/memory/decisions-log.md` for full rationale.
 - For one-off theme overrides, use the `sx` prop pattern
 - Every component MUST accept and forward the `sx` prop for consumer overrides