feat(docs-site): use the funk wordmark logo instead of "punktfunk" text

Swap the plain "punktfunk" text in the nav and landing hero for the real
brand wordmark from the marketing site. The source asset is a single
light-violet variant (made for dark surfaces), so it's painted as a CSS
mask and coloured per theme — deep-violet on light, light-violet on dark —
to stay legible with the docs' light/dark toggle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs-site/src/lib/layout.shared.tsx

@@ -1,5 +1,6 @@
 import type { BaseLayoutProps } from 'fumadocs-ui/layouts/shared'
 import BrandMark from '@/components/BrandMark'
+import Wordmark from '@/components/Wordmark'
 
 // Shared chrome (nav title, links) for both the docs layout and the home layout.
 // The lens mark + wordmark mirror the punktfunk marketing site's header.
@@ -9,7 +10,7 @@ export function baseOptions(): BaseLayoutProps {
       title: (
         <>
           <BrandMark className="size-6" />
-          <span className="font-display font-semibold tracking-tight">punktfunk</span>
+          <Wordmark className="h-4" />
         </>
       ),
     },