fix(chat-ui): fix CSS pipeline and Tailwind source scanning

- Import chat-ui.css via CSS @import in main.css (not JS import)
  so @layer directives go through Tailwind's compilation
- Add @source directive for packages/chat-ui so Tailwind v4
  scans the package for utility classes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/main/src/main.css

@@ -1,5 +1,8 @@
 @import "tailwindcss";
 @import "tw-animate-css";
+@import "@xtablo/chat-ui/src/chat-ui.css";
+
+@source "../../../packages/chat-ui/src/**/*.{ts,tsx}";
 
 @custom-variant dark (&:is(.dark *));
 

packages/chat-ui/src/index.ts

@@ -1,5 +1,3 @@
-import "./chat-ui.css"
-
 // Core components
 export {
   ChatProvider,