Consolidate theme radius/shadow props and make rounded utilities responsive

- Remove duplicate roundedness/shadowLevel props (keep radius/shadow)
- Switch globals.css radius scale to proportional (square→pill works)
- Replace rounded-full with rounded-md on theme-driven elements
- Remove banner props from Navigation, drop publishing overlay

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

components/hero/hero.tsx

@@ -97,7 +97,7 @@ export function Hero({
             <Link
               to={primaryCta.href || "#"}
               className={cn(
-                "inline-flex items-center justify-center rounded-full px-6 py-3 text-sm font-medium tracking-wide transition-opacity hover:opacity-90",
+                "inline-flex items-center justify-center rounded-md px-6 py-3 text-sm font-medium tracking-wide transition-opacity hover:opacity-90",
                 isDark ? "bg-white text-black" : "bg-foreground text-background",
               )}
             >
@@ -108,7 +108,7 @@ export function Hero({
             <Link
               to={secondaryCta.href || "#"}
               className={cn(
-                "inline-flex items-center justify-center rounded-full border px-6 py-3 text-sm font-medium tracking-wide transition-opacity hover:opacity-80",
+                "inline-flex items-center justify-center rounded-md border px-6 py-3 text-sm font-medium tracking-wide transition-opacity hover:opacity-80",
                 isDark ? "border-white text-white" : "border-foreground text-foreground",
               )}
             >