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/cta/cta.tsx

@@ -63,7 +63,7 @@ export function CTA({
           {primaryCta?.label ? (
             <Link
               to={primaryCta.href || "#"}
-              className="inline-flex items-center justify-center rounded-full bg-white px-6 py-3 text-sm font-medium tracking-wide text-black hover:opacity-90"
+              className="inline-flex items-center justify-center rounded-md bg-white px-6 py-3 text-sm font-medium tracking-wide text-black hover:opacity-90"
             >
               {primaryCta.label}
             </Link>
@@ -71,7 +71,7 @@ export function CTA({
           {secondaryCta?.label ? (
             <Link
               to={secondaryCta.href || "#"}
-              className="inline-flex items-center justify-center rounded-full border border-white px-6 py-3 text-sm font-medium tracking-wide text-white hover:bg-white/10"
+              className="inline-flex items-center justify-center rounded-md border border-white px-6 py-3 text-sm font-medium tracking-wide text-white hover:bg-white/10"
             >
               {secondaryCta.label}
             </Link>