fix(avatar): pair bg-secondary with text-secondary-foreground

The Avatar primitive paired bg-secondary with text-foreground, which
isn't a Shadcn-designed pair. In themes whose secondary is a bright
color (Starry Night dark: bright yellow) the global foreground
(near-white) lands on top and the initial becomes unreadable.

Switch to text-secondary-foreground so contrast is whatever the theme
author guaranteed for that pair. Pre-emptively protects any future
theme since every theme must keep secondary/secondary-foreground
contrast valid.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/ui/avatar/index.ts

@@ -5,7 +5,7 @@ export { default as AvatarFallback } from './AvatarFallback.vue'
 export { default as AvatarImage } from './AvatarImage.vue'
 
 export const avatarVariant = cva(
-  'inline-flex items-center justify-center font-normal text-foreground select-none shrink-0 bg-secondary overflow-hidden',
+  'inline-flex items-center justify-center font-normal text-secondary-foreground select-none shrink-0 bg-secondary overflow-hidden',
   {
     variants: {
       size: {