A cleaner Koda page that matches the dashboard

The Koda page now feels like the rest of the dashboard instead of a separate site.

• Follows your theme — light or dark, with the standard page header, cards, and the official Koda wordmark.
• Spreads across the page — the early-access, setup, and connected views fill the width like every other section instead of sitting in a narrow column.
• Easier to scan — a tidier feature preview while you're on the waitlist, a side-by-side setup wizard once you're in, and clearer session and install stats when Koda's connected.