Add robots.ts

[ResourceMint]

Closes #119.

What this changes

Adds src/app/robots.ts. src/app/sitemap.ts already existed on main and covers the static routes, docsPages, and /legal/*, so only the robots half of the issue was outstanding.

The route allows crawling, points at ${site.url}/sitemap.xml, and disallows /auth/, /login, and the PWA /offline fallback.

Per-city pages (#127) have not landed yet, so nothing was added for them.

Type of change

• New public place(s)
• New or updated benefit guide
• New or updated resource link
• Code or fix
• Docs

Proof (required for new public places)

N/A, no places added in this PR.

• Each place's rating is 4.0 or higher. - N/A
• Each place has 50 or more reviews. - N/A
• Coordinates point to the correct entrance. - N/A
• The JSON record stops at gmaps_link and added_by (no proof fields committed). - N/A

Checklist

• The site hosts no copyrighted files; resource and paper changes are links only.
• No em dashes in any copy.

Verifying

npx tsc --noEmit and npx eslint src/app/robots.ts are clean. npm run build lists both /robots.txt and /sitemap.xml as prerendered static routes.

Generated robots.txt:

User-Agent: *
Allow: /
Disallow: /auth/
Disallow: /login
Disallow: /offline

Sitemap: https://studyymap.com/sitemap.xml

Generated sitemap.xml: 25 URLs, no duplicates (sort | uniq -d empty), nothing under /auth or /login.

[vercel]

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