Add photo galleries API and frontend for public and admin viewing.

Introduces the Go photo-api service, nginx/systemd deploy wiring, and Next.js gallery/lightbox pages so event photos can be managed and browsed.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/api/index.ts

@@ -17,3 +17,11 @@ export { siteSettingsApi } from './siteSettings';
 export { legalSettingsApi } from './legalSettings';
 export { legalPagesApi } from './legalPages';
 export { faqApi } from './faq';
+export { photosApi } from './photos';
+export type {
+  Photo,
+  PhotoGallery,
+  PhotoGalleryEvent,
+  GalleryVisibility,
+  CreateGalleryInput,
+} from './photos';