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

content/gallery.yaml.example

@@ -0,0 +1,44 @@
+# ── Gallery Configuration ──────────────────────────────────────
+# Define which Immich albums to publish and how to organize them.
+#
+# Find album UUIDs in Immich: Albums → click album → UUID in the URL bar.
+# Find asset UUIDs: click a photo → UUID in the URL bar.
+
+# Hero image(s) shown on the homepage (Immich asset UUIDs).
+# Use a single UUID for a static image, or a list for a crossfade carousel.
+hero: 00000000-0000-0000-0000-000000000000
+# hero:
+#   - 00000000-0000-0000-0000-000000000000
+#   - 11111111-1111-1111-1111-111111111111
+#   - 22222222-2222-2222-2222-222222222222
+
+# Standalone albums — shown directly on the homepage as cards
+albums:
+  - 11111111-1111-1111-1111-111111111111
+  - 22222222-2222-2222-2222-222222222222
+
+# Show camera/lens EXIF on photo hover (default: true)
+# exifOnHover: false
+
+# Photo grid layout — customize columns, gap, aspect ratio, and mode.
+# grid:
+#   columns: 3        # default: 3
+#   gap: 12            # pixels, default: 12
+#   aspectRatio: "1"   # "1", "3/2", "auto", etc. default: "1"
+#   layout: masonry    # "masonry" or "uniform", default: "masonry"
+
+# Subpages — group albums into collections at /subpage-slug/album-slug
+subpages:
+  - name: Japan
+    grid:                  # override global grid for this subpage
+      columns: 4
+      layout: uniform
+      aspectRatio: "3/2"
+    albums:
+      - 33333333-3333-3333-3333-333333333333  # Tokyo
+      - 44444444-4444-4444-4444-444444444444  # Kyoto
+
+  - name: Wedding – Smith
+    password: clientpass123  # visitors must enter this to view
+    albums:
+      - 55555555-5555-5555-5555-555555555555