Restyle landing page with omarchy-style block art logo and self-hosted font

- Block art logo using ███▄▀ characters in omarchy font style (8 rows tall, 3-char strokes)
- Self-host Cascadia Code SemiBold for tight block character rendering
- Two-tone blue/purple color split between CALEND and ARCHY
- Update tagline to "A keyboard-first terminal calendar"
- Remove terminal SVG title bar

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

Author: sovanesyan