Add automated legal page content lint (`legal/[slug]/page.tsx`)

[Codex723]

Summary

Add a check ensuring every legal slug referenced in nav/footer actually resolves to content, avoiding silent 404s on legal pages.

Difficulty

Good First Issue — estimated effort: ~1-3 hours. Labels: frontend, good-first-issue, good-first-issue

Where to Work

• legal/[slug]/page.tsx

How to Approach This

1. Locate the relevant page under src/app/(app)/ or component under src/components/.
2. Match the existing Tailwind utility-class conventions already used in that file — don't introduce a new styling approach.
3. If adding new interactive state, prefer local useState/useEffect consistent with how nearby components in the file already manage state.
4. Test the change at both desktop and mobile breakpoints (e.g. Chrome DevTools responsive mode) before opening a PR.
5. Run npm run lint and npm run build locally to confirm no type or lint errors were introduced.
6. If you added a new reusable piece of UI, consider whether it belongs in src/components/ instead of being page-local.

Acceptance Criteria

• Behavior/UI described above is implemented in the file(s) listed under "Files Likely Affected".
• Verified visually at both desktop and mobile widths.
• Keyboard accessible where interactive (tab order, visible focus state) if applicable.
• No new TypeScript, lint, or build errors (npm run lint, npm run build).
• Existing tests still pass; new tests added if this issue includes a testing component.

Notes for Contributors

Comment on this issue before starting so it can be assigned to you and duplicate work is avoided. If the described approach doesn't quite fit once you're in the code (e.g. the file has moved, or there's a cleaner way to do it), that's fine — leave a comment explaining the deviation in your PR description rather than silently changing scope.

[Vyacheslav-Tomashevskiy]

Opened a fix: #513 — adds a vitest regression test that scans every /legal/<slug> reference in CookieBanner.tsx, landing-client.tsx, and sitemap.ts and checks each one against the PAGES map in src/app/legal/[slug]/page.tsx, failing with the exact dangling file+slug if one is ever unlinked or removed. Ran locally (4/4 new + 10/10 full suite, tsc/eslint clean) and manually confirmed it catches a broken link before opening the PR.