Apply brand identity to the frontend (ink + bronze + paper)

Replaces the default black/gray with the docs/brand palette: warm ink text on paper surfaces, bronze accent, serif headings and the Origin-mark wordmark in the header, favicon, and the 'where it came from matters' tagline. Light/dark adapt via CSS vars (ink/paper flip); bronze and paper are constant. Tailwind v4 @theme exposes bronze/paper/ink tokens and the serif stack. Buttons/inputs/cards restyled to match; brand SVGs vendored into public/.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

frontend/components/ui/card.tsx

@@ -5,7 +5,10 @@ import { cn } from "@/lib/utils";
 export function Card({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) {
   return (
     <div
-      className={cn("rounded-lg border border-neutral-200 bg-white/50 shadow-sm", className)}
+      className={cn(
+        "rounded-lg border border-[var(--border)] bg-[var(--surface)] shadow-sm",
+        className,
+      )}
       {...props}
     />
   );
@@ -16,7 +19,7 @@ export function CardHeader({ className, ...props }: React.HTMLAttributes<HTMLDiv
 }
 
 export function CardTitle({ className, ...props }: React.HTMLAttributes<HTMLHeadingElement>) {
-  return <h3 className={cn("text-lg font-semibold", className)} {...props} />;
+  return <h3 className={cn("font-serif text-lg font-semibold", className)} {...props} />;
 }
 
 export function CardContent({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) {