feat(docs-site): add the site-wide footer, shared with the marketing site

Pull the same footer from the shared unom CMS global (cms.unom.io) and render
it globally under both the home and docs layouts. Read-only typed fetch in a
server-side root loader (falls back to null on a CMS hiccup). Root-relative
links target the marketing site, so they're resolved against its origin (the
docs don't host /legal/* etc.); themed with Fumadocs tokens for light/dark.

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

docs-site/src/components/Footer.tsx

@@ -0,0 +1,51 @@
+import { getRouteApi } from '@tanstack/react-router'
+import type { NavigationLink, NavigationSection } from '@/lib/cms'
+
+const rootApi = getRouteApi('__root__')
+
+// The docs share the marketing site's footer (same CMS global). Root-relative
+// links target the website, so resolve them against its origin — the docs don't
+// host /legal/* etc. themselves. Mirrors the website Footer, themed for docs.
+const SITE_URL = 'https://punktfunk.unom.io'
+const resolve = (to?: string | null) =>
+  to ? (to.startsWith('/') ? `${SITE_URL}${to}` : to) : '#'
+
+export default function Footer() {
+  const { footer } = rootApi.useLoaderData()
+  const sections: NavigationSection[] = footer?.sections ?? []
+  const tagline = footer?.tagline?.trim()
+
+  if (!sections.length && !tagline) return null
+
+  return (
+    <footer className="border-t border-fd-border bg-fd-card">
+      <div className="mx-auto flex w-full max-w-6xl flex-row flex-wrap gap-12 px-4 py-12 sm:px-6">
+        {sections.map((group, gi) => (
+          <div key={group.id ?? gi}>
+            {group.title && (
+              <h3 className="mb-2 text-sm font-semibold text-fd-foreground">
+                {group.title}
+              </h3>
+            )}
+            <div className="flex flex-col gap-1">
+              {(group.entries ?? []).map((item: NavigationLink, i) => (
+                <a
+                  key={item.id ?? `${item.to}-${i}`}
+                  href={resolve(item.to)}
+                  className="text-sm text-fd-muted-foreground transition-colors hover:text-fd-foreground"
+                >
+                  {item.label}
+                </a>
+              ))}
+            </div>
+          </div>
+        ))}
+        {tagline && (
+          <p className="ml-auto self-end text-sm text-fd-muted-foreground">
+            {tagline}
+          </p>
+        )}
+      </div>
+    </footer>
+  )
+}