docs: add GuidePage documentation (refs #203)

- Create CLAUDE.md for GuidePage directory with architecture docs
- Create CLAUDE.md index for pages/ directory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/CLAUDE.md

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+# frontend/src/pages/
+
+Page-level components and routing targets.
+
+## Files
+
+| File | What | When to read |
+| ---- | ---- | ------------ |
+| `HomePage.tsx` | Public landing page (Home, Features, About, Guide, Sign Up, Login) | Modifying public site |
+| `SettingsPage.tsx` | Settings page component | User settings |
+| `SecuritySettingsPage.tsx` | Security settings page | Security/privacy settings |
+
+## Subdirectories
+
+| Directory | What | When to read |
+| --------- | ---- | ------------ |
+| `GuidePage/` | Public user guide at `/guide` (10 sections, TOC, screenshots) | Guide content or structure |
+| `HomePage/` | HomePage sub-components (HeroCarousel, FeaturesGrid) | Landing page features |
+| `admin/` | Admin-only pages | Admin functionality |
+| `__tests__/` | Page-level integration tests | Testing pages |

frontend/src/pages/GuidePage/CLAUDE.md

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+# frontend/src/pages/GuidePage/
+
+Public-facing user guide page at `/guide`. Renders `docs/USER-GUIDE.md` content as styled React components with screenshots.
+
+## Files
+
+| File | What | When to read |
+| ---- | ---- | ------------ |
+| `GuidePage.tsx` | Main page component with layout, nav bar, and section rendering | Modifying page structure or navigation |
+| `GuideTableOfContents.tsx` | Sticky sidebar TOC (desktop) / collapsible accordion TOC (mobile) | Modifying TOC behavior or styling |
+| `guideTypes.ts` | Section metadata (id, title, subSections) used by TOC and anchors | Adding/renaming sections |
+
+## Subdirectories
+
+| Directory | What | When to read |
+| --------- | ---- | ------------ |
+| `components/` | Shared components (GuideScreenshot, GuideTable) | Modifying screenshot or table rendering |
+| `sections/` | 10 content section components (one per guide chapter) | Updating guide content |
+
+## Architecture
+
+- Static JSX components (no react-markdown dependency); content changes require editing section files directly
+- Each section is 150-250 lines of JSX; individual files prevent a 2000+ line monolith
+- GuideScreenshot provides consistent lazy loading (`loading="lazy"`), responsive sizing, and WebP support across all sections
+- GuideTable renders MUI Table from `headers[]` and `rows[][]` arrays, preventing verbose MUI Table boilerplate in each section
+- The page has its own public nav bar (matching HomePage style) because it is accessible without authentication
+- `/guide` route is detected in App.tsx and rendered outside the authenticated `/garage/*` shell
+
+## Key Patterns
+
+- Section anchor IDs must match `guideTypes.ts` section IDs for TOC smooth scroll to work
+- Screenshots stored in `frontend/public/guide/` as static assets with `loading="lazy"`
+- TOC uses `window.innerWidth < 768` breakpoint: sidebar on desktop, MUI Accordion on mobile
+- Guide link in HamburgerDrawer uses `window.location.href` (not Zustand navigation) because `/guide` is outside the `/garage/*` shell