- Replace HSL-based indigo theme with official shadcn violet OKLCH theme
in globals.css for proper contrast in both light and dark mode
- Update tailwind.config.ts to use var(--...) instead of hsl(var(--...))
for OKLCH color space compatibility
- Fix Radix UI crash: replace SelectItem value="" with "__none__" sentinel
in HostDialogs.tsx and L4HostDialogs.tsx (empty string value is invalid)
Form action parsers already return null for non-numeric values
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>