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/app/(public)/photos/[slug]/page.tsx

@@ -0,0 +1,51 @@
+import type { Metadata } from 'next';
+import { Suspense } from 'react';
+import type { PhotoGallery, Photo } from '@/lib/api';
+import GalleryClient from './GalleryClient';
+
+const photoApiUrl = process.env.PHOTO_API_URL || 'http://localhost:3003';
+
+interface PageProps {
+  params: { slug: string };
+}
+
+// Public galleries render server-side (SEO + fast first paint); link and
+// ticket galleries return null here and are fetched client-side with the
+// viewer's token / share token.
+async function getPublicGallery(
+  slug: string
+): Promise<{ gallery: PhotoGallery; photos: Photo[] } | null> {
+  try {
+    const res = await fetch(
+      `${photoApiUrl}/api/photos/public/galleries/${encodeURIComponent(slug)}`,
+      { next: { revalidate: 300 } }
+    );
+    if (!res.ok) return null;
+    return await res.json();
+  } catch {
+    return null;
+  }
+}
+
+export async function generateMetadata({ params }: PageProps): Promise<Metadata> {
+  const data = await getPublicGallery(params.slug);
+  if (!data) {
+    return { title: 'Photo Gallery', robots: { index: false } };
+  }
+  return {
+    title: `${data.gallery.title} – Photos`,
+    description:
+      data.gallery.description ||
+      `Photos from ${data.gallery.title}, a Spanglish language exchange event in Asunción.`,
+  };
+}
+
+export default async function GalleryPage({ params }: PageProps) {
+  const initial = await getPublicGallery(params.slug);
+  return (
+    // Suspense boundary required by useSearchParams() in the client child.
+    <Suspense>
+      <GalleryClient slug={params.slug} initial={initial} />
+    </Suspense>
+  );
+}