chore: update sitemap with missing static routes

[iryuken]

Summary:

Added missing static routes to src/app/sitemap.ts to ensure sitemap.xml includes all relevant pages, improving SEO and indexing. The added routes cover key pages such as /cfp-guidelines, /convince-my-boss, /job-board, /our-team, /tickets, and /welcome-guide.
Additionally, integrated FEATURE_FLAGS check into sitemap.ts
to ensure that only enabled features/pages are included in the sitemap. For example, if WELCOME_GUIDE is disabled, its route will not appear in the generated sitemap.xml.

Issue Link:

Issue Link:

fix #71

PR Checks:

• Code is properly formatted (executed make pre-push command local equivalent).
• No ESLint warnings (verified with local build/lint).
• UI Changes are responsive (checked in the responsive view).
• Performance is maintained (Lighthouse report reviewed).
• User experience (UX) considerations are met.
• Accessibility is supported (validated with accessibility tools).
• For new features, a feature flag has been added.
• All assets are optimized for minimal file size.
• File names, asset names, and component names follow consistent naming conventions.

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