Migrate Tailwind styles to design-system package (#5794)

## Summary

Consolidates Tailwind configuration and styles into a shared
`@comfyorg/design-system` package for reuse across monorepo apps.

The goal was not to make changes to how the design system works; merely
to separate it cleanly. I _would_ strongly recommend some drastic
sweeping changes, however I believe that should be done after the
migration.

## Changes

- **What**: Migrates CSS files, Tailwind config, and custom icons to
design-system package
- **Dependencies**: Moves `@iconify-json/lucide` and `@iconify/tailwind`
to design-system package

src/assets/css/fonts.css

@@ -1,17 +0,0 @@
-/* Inter Font Family */
-
-@font-face {
-  font-family: 'Inter';
-  src: url('/fonts/inter-latin-normal.woff2') format('woff2');
-  font-weight: 100 900;
-  font-style: normal;
-  font-display: swap;
-}
-
-@font-face {
-  font-family: 'Inter';
-  src: url('/fonts/inter-latin-italic.woff2') format('woff2');
-  font-weight: 100 900;
-  font-style: italic;
-  font-display: swap;
-}