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

lib/immichLoader.ts

@@ -0,0 +1,24 @@
+/**
+ * Custom next/image loader for Immich proxy.
+ *
+ * Referenced by next.config.ts via images.loaderFile.
+ * Generates URLs that point to our /api/image proxy route,
+ * passing width and quality as query parameters.
+ *
+ * The src passed to next/image should already be a full proxy URL
+ * (e.g. /api/image/<token>?size=preview). This loader appends
+ * w and q params for responsive srcset generation.
+ */
+
+'use client';
+
+interface ImageLoaderParams {
+    src: string;
+    width: number;
+    quality?: number;
+}
+
+export default function immichLoader({ src, width, quality }: ImageLoaderParams): string {
+    const separator = src.includes('?') ? '&' : '?';
+    return `${src}${separator}w=${width}&q=${quality || 75}`;
+}