feat: make /unternehmen hero image admin-editable too

Same gap as /imkerei and /herkunft (previous commit): last remaining
hardcoded PlaceholderImage in the app, now wired to the same
content-registry "pages" group / ContentImage pattern.

Verified: tsc clean, 151/151 tests pass, page still returns 200.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/app/unternehmen/page.tsx

@@ -1,9 +1,10 @@
 import type { Metadata } from "next";
 import { Container, SectionHeading } from "@/components/ui";
-import { PlaceholderImage } from "@/components/placeholder-image";
+import { ContentImage } from "@/components/content-image";
 import { BusinessInquiryForm } from "@/components/business-inquiry-form";
 import { getLocale } from "@/i18n/locale";
 import { getDictionary } from "@/i18n/get-dictionary";
+import { getContentValue } from "@/lib/content";
 
 export async function generateMetadata(): Promise<Metadata> {
   const t = getDictionary(await getLocale());
@@ -15,10 +16,18 @@ export async function generateMetadata(): Promise<Metadata> {
 }
 
 export default async function UnternehmenPage() {
-  const t = getDictionary(await getLocale());
+  const locale = await getLocale();
+  const t = getDictionary(locale);
+  const image = await getContentValue("unternehmen.image", locale);
   return (
     <div>
-      <PlaceholderImage tone="honey" className="h-[45vh] min-h-[320px] w-full" label={t.unternehmenPage.eyebrow} />
+      <ContentImage
+        src={image || null}
+        alt={t.unternehmenPage.eyebrow}
+        tone="honey"
+        className="h-[45vh] min-h-[320px] w-full"
+        label={t.unternehmenPage.eyebrow}
+      />
       <Container className="py-20">
         <SectionHeading
           level="h1"