feat: recolor BrandLogo to cyan gradient, split BrandWordmark for gradient Flow text

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

frontend/src/components/common/BrandWordmark.tsx

@@ -5,20 +5,17 @@ interface BrandWordmarkProps {
   className?: string
 }
 
-/**
- * ResolutionFlow wordmark — clean white text.
- * sm for header/navbar, lg for login/register pages.
- */
 export function BrandWordmark({ size = 'sm', className }: BrandWordmarkProps) {
   return (
     <span
       className={cn(
-        'font-semibold tracking-tight text-white',
+        'font-heading font-bold tracking-tight',
         size === 'sm' ? 'text-xl' : 'text-3xl',
         className
       )}
     >
-      ResolutionFlow
+      <span className="text-foreground">Resolution</span>
+      <span className="text-gradient-brand">Flow</span>
     </span>
   )
 }