[TRIVIAL] Build the landing page hero section UI

[spiffamani]

Summary

Improve the existing landing page hero section in frontend/src/pages/LandingPage.tsx. The current version is basic — make it visually polished with proper spacing, gradient text, and a clean call-to-action section.

Acceptance Criteria

• Hero headline uses gradient text (indigo to purple)
• "Find Work" and "Hire a Freelancer" buttons are clearly styled
• Layout is responsive on mobile and desktop
• Tailwind CSS used throughout (no custom CSS files)