fix(improvements): replace PNG logo with SVG dark/light variants, add website links, redirect about page

- Replace unoplat_logo.png with proper SVG logos using dark:hidden/dark:block for theme switching
- Add website (unoplat.io) link to header social icons, footer social + explore sections
- Redirect /about page to https://www.unoplat.io
- Reduce logo size from h-9 to h-7 for better proportion with nav text

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: JayGhiya