feat: photography features & image optimizations

- Hero carousel: gallery.yaml hero accepts single UUID or array, crossfade component
- Full-bleed single albums: subpages with 1 album skip grid, render photos directly
- EXIF on hover: camera/lens/focal length overlay on grid items (toggle via exifOnHover)
- Customizable grid: columns/gap/aspectRatio/layout (masonry|uniform) via gallery.yaml
- Per-subpage grid overrides: each subpage can override global grid config
- True masonry: per-image aspect ratios from EXIF dimensions
- next/image migration: homepage hero, album covers, grid thumbnails, about portrait
- ThumbHash blur placeholders and dominant color backgrounds
- Custom next/image loader via image proxy with width/quality params
- Lightbox fade-in transition with dominant color background
- Password-protected subpages, health check, rate limiting, OG images

app/layout.tsx

@@ -8,9 +8,24 @@ import Link from 'next/link';
 import './globals.css';
 import { SubpageNav } from '@/components/SubpageNav';
 
+const siteTitle = process.env.SITE_TITLE || 'Gallery';
+const siteDescription = 'A curated photography portfolio';
+
 export const metadata: Metadata = {
-  title: process.env.SITE_TITLE || 'Gallery',
-  description: 'A curated photography portfolio',
+  title: siteTitle,
+  description: siteDescription,
+  openGraph: {
+    title: siteTitle,
+    description: siteDescription,
+    type: 'website',
+    images: [`/api/og?title=${encodeURIComponent(siteTitle)}`],
+  },
+  twitter: {
+    card: 'summary_large_image',
+    title: siteTitle,
+    description: siteDescription,
+    images: [`/api/og?title=${encodeURIComponent(siteTitle)}`],
+  },
 };
 
 export default function RootLayout({
@@ -27,6 +42,9 @@ export default function RootLayout({
               Home
             </Link>
             <SubpageNav />
+            <Link href="/about" className="header__nav-link">
+              About
+            </Link>
           </nav>
         </header>
         <main className="main">{children}</main>