feat: add quilted layout, fix mosaic, and backfill photo dimensions (#146)

- Add migration to backfill width/height for existing photos without dimensions
- Replace justified masonry mode with quilted layout (mixed sizes based on aspect ratio)
- Rewrite mosaic layout to use proper CSS Grid with span rules
- Fix theme not being applied after gallery login
- Improve columns mode distribution using shortest-column algorithm
- Apply gallery theme regardless of authentication status

backend/migrations/core/064_backfill_photo_dimensions.js

@@ -0,0 +1,105 @@
+/**
+ * Migration: Backfill photo dimensions
+ *
+ * This migration extracts width/height from existing photos that don't have
+ * these dimensions stored. This is needed for aspect-ratio-aware layouts
+ * (masonry, mosaic, justified) to work properly.
+ */
+
+const path = require('path');
+const fs = require('fs');
+
+exports.up = async function(knex) {
+  // Check if the width/height columns exist
+  const hasWidth = await knex.schema.hasColumn('photos', 'width');
+  const hasHeight = await knex.schema.hasColumn('photos', 'height');
+
+  if (!hasWidth || !hasHeight) {
+    console.log('[Migration 064] Width/height columns not found, skipping backfill');
+    return;
+  }
+
+  // Get storage path
+  const storagePath = process.env.STORAGE_PATH || path.join(__dirname, '../../../storage');
+
+  // Find photos without dimensions
+  const photos = await knex('photos')
+    .whereNull('width')
+    .orWhereNull('height')
+    .select('id', 'path', 'filename', 'media_type');
+
+  console.log(`[Migration 064] Found ${photos.length} photos without dimensions`);
+
+  if (photos.length === 0) {
+    return;
+  }
+
+  // Import sharp dynamically (only needed during migration)
+  let sharp;
+  try {
+    sharp = require('sharp');
+  } catch (err) {
+    console.error('[Migration 064] Sharp not available, skipping backfill:', err.message);
+    return;
+  }
+
+  let updated = 0;
+  let failed = 0;
+
+  for (const photo of photos) {
+    try {
+      // Skip videos - they need ffprobe for metadata
+      if (photo.media_type === 'video') {
+        continue;
+      }
+
+      // Construct the full file path
+      let fullPath;
+      if (photo.path) {
+        // Path is relative to events/active directory
+        fullPath = path.join(storagePath, 'events/active', photo.path);
+      } else {
+        console.warn(`[Migration 064] Photo ${photo.id} (${photo.filename}) has no path, skipping`);
+        continue;
+      }
+
+      // Check if file exists
+      if (!fs.existsSync(fullPath)) {
+        console.warn(`[Migration 064] Photo ${photo.id} file not found: ${fullPath}`);
+        failed++;
+        continue;
+      }
+
+      // Extract dimensions using sharp
+      const metadata = await sharp(fullPath).metadata();
+
+      if (metadata.width && metadata.height) {
+        await knex('photos')
+          .where('id', photo.id)
+          .update({
+            width: metadata.width,
+            height: metadata.height
+          });
+        updated++;
+
+        if (updated % 50 === 0) {
+          console.log(`[Migration 064] Updated ${updated} photos...`);
+        }
+      } else {
+        console.warn(`[Migration 064] Could not extract dimensions for photo ${photo.id}`);
+        failed++;
+      }
+    } catch (err) {
+      console.error(`[Migration 064] Error processing photo ${photo.id}:`, err.message);
+      failed++;
+    }
+  }
+
+  console.log(`[Migration 064] Completed: ${updated} updated, ${failed} failed`);
+};
+
+exports.down = async function(knex) {
+  // This migration only adds data, no rollback needed
+  // We don't want to null out dimensions on rollback as they're still valid
+  console.log('[Migration 064] Rollback: No action needed (data-only migration)');
+};