Feat/sitemap build integration

[MerlinTheWhiz]

Description

Integrates the existing sitemap generation script into the build pipeline so that sitemap.xml is automatically regenerated after every production build. Previously, scripts/generate-sitemap.ts existed and was callable via pnpm generate:sitemap but was never invoked during pnpm build, causing production deployments to ship without an up-to-date sitemap.

Changes made:

• package.json: Added "postbuild": "pnpm run generate:sitemap" so the sitemap regenerates automatically after next build
• scripts/generate-sitemap.ts:
  • Replaced HTTP fetch() of /api/courses with a direct import from @/lib/course-config — this is more reliable at build time since no API server is running
  • Expanded static route coverage to include /leaderboard, /certificates, /support, /privacy, /release-notes
  • Added validateSitemap() function that checks URL count (≤ 50,000), file size (≤ 50MB), and HTTPS compliance
  • Running pnpm build now produces public/sitemap.xml
• DOCKER_DEPLOYMENT.md: Added an SEO section documenting how to verify and submit the sitemap to Google Search Console after deployment

Related Issue

Closes #770

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Checklist

• Code follows project style guidelines
• Self-review completed
• No console errors
• Uses Lucide icons consistently
• Responsive design implemented
• Starknet best practices followed

[drips-wave]

@MerlinTheWhiz Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[RUKAYAT-CODER]

Thank you for contributing to the project.