fix: lightbox watermark loading, white label translations, and dynamic footer year

- Fix watermarked images not opening in lightbox (add /api prefix to photo URLs)
- Add i18n translations for 'White Label' and 'Hide Powered by' branding settings
- Add complete logo customization translations (EN and DE)
- Replace hardcoded © 2024 with dynamic current year in footer
- Use company name from settings in default footer text

frontend/src/utils/photoUrl.ts

@@ -12,10 +12,10 @@ interface PhotoUrlOptions {
  */
 export function getPhotoUrl({ slug, photo, watermarkEnabled = false, token }: PhotoUrlOptions): string {
   if (watermarkEnabled && token) {
-    // Use the watermarked photo endpoint
-    return `/gallery/${slug}/photo/${photo.id}`;
+    // Use the watermarked photo endpoint (needs /api prefix)
+    return `/api/gallery/${slug}/photo/${photo.id}`;
   }
-  
+
   // Use the static photo URL
   return photo.url;
 }