feat: sort photos by capture date with configurable default sort (#283)

Add per-event default photo sort setting with 6 options:
- Upload Date (Newest/Oldest First)
- Date Taken (Newest/Oldest First) — uses EXIF captured_at
- Filename (A-Z / Z-A)

Backend:
- Migration 077 adds default_photo_sort column to events table
- Event create/update handlers accept and validate the setting
- Gallery info endpoint returns default_photo_sort for frontend

Frontend:
- "Date Taken" added to gallery sort dropdown (alongside Date, Name,
  Size, Rating)
- Gallery initializes with event's default sort instead of hardcoded
  "date"
- "Default Photo Sort" dropdown in event create and edit forms
- Photos without EXIF dates fall back to upload date

i18n: All 5 locales (EN, DE, NL, PT, RU) updated with sort labels.

Closes #283

frontend/src/components/gallery/GallerySidebar.tsx

@@ -356,7 +356,7 @@ export const GallerySidebar: React.FC<GallerySidebarProps> = ({
                     <button
                       key={option.value}
                       onClick={() => {
-                        onSortChange(option.value as 'date' | 'name' | 'size' | 'rating');
+                        onSortChange(option.value as 'date' | 'name' | 'size' | 'rating' | 'capture_date');
                         if (isMobile) onClose();
                       }}
                       className={`

frontend/src/components/gallery/GalleryView.tsx

@@ -42,6 +42,25 @@ interface GalleryViewProps {
   };
 }
 
+// Convert default_photo_sort DB value to internal sortBy state
+const parseDefaultPhotoSort = (defaultSort?: string): { sortBy: 'date' | 'name' | 'size' | 'rating' | 'capture_date'; sortDesc: boolean } => {
+  switch (defaultSort) {
+    case 'upload_date_asc':
+      return { sortBy: 'date', sortDesc: false };
+    case 'capture_date_desc':
+      return { sortBy: 'capture_date', sortDesc: true };
+    case 'capture_date_asc':
+      return { sortBy: 'capture_date', sortDesc: false };
+    case 'filename_asc':
+      return { sortBy: 'name', sortDesc: false };
+    case 'filename_desc':
+      return { sortBy: 'name', sortDesc: true };
+    case 'upload_date_desc':
+    default:
+      return { sortBy: 'date', sortDesc: true };
+  }
+};
+
 export const GalleryView: React.FC<GalleryViewProps> = ({ slug, event }) => {
   const { t } = useTranslation();
   const { logout, isClient } = useGalleryAuth();
@@ -50,6 +69,7 @@ export const GalleryView: React.FC<GalleryViewProps> = ({ slug, event }) => {
   const [selectedCategoryId, setSelectedCategoryId] = useState<number | string | null>(null);
   const [searchTerm, setSearchTerm] = useState('');
   const [sortBy, setSortBy] = useState<'date' | 'name' | 'size' | 'rating' | 'capture_date'>('date');
+  const [defaultSortApplied, setDefaultSortApplied] = useState(false);
   const [brandingSettings, setBrandingSettings] = useState<any>(null);
   const [showUploadModal, setShowUploadModal] = useState(false);
   const [sidebarOpen, setSidebarOpen] = useState(false);
@@ -103,6 +123,15 @@ export const GalleryView: React.FC<GalleryViewProps> = ({ slug, event }) => {
     }
   }, [data?.event?.protection_level]);
 
+  // Apply default photo sort from event settings
+  useEffect(() => {
+    if (!defaultSortApplied && data?.event?.default_photo_sort) {
+      const { sortBy: defaultSortBy } = parseDefaultPhotoSort(data.event.default_photo_sort);
+      setSortBy(defaultSortBy);
+      setDefaultSortApplied(true);
+    }
+  }, [data?.event?.default_photo_sort, defaultSortApplied]);
+
   // Get individual protection settings from event
   const disableRightClick = data?.event?.disable_right_click === true;
   const enableDevtoolsProtection = data?.event?.enable_devtools_protection === true;

frontend/src/components/gallery/PhotoFilterBar.tsx

@@ -25,8 +25,8 @@ interface PhotoFilterBarProps {
   onCategoryChange: (categoryId: number | string | null) => void;
   searchTerm: string;
   onSearchChange: (term: string) => void;
-  sortBy: 'date' | 'name' | 'size' | 'rating';
-  onSortChange: (sort: 'date' | 'name' | 'size' | 'rating') => void;
+  sortBy: 'date' | 'name' | 'size' | 'rating' | 'capture_date';
+  onSortChange: (sort: 'date' | 'name' | 'size' | 'rating' | 'capture_date') => void;
   photoCount: number;
   // Feedback filter props
   feedbackEnabled?: boolean;
@@ -82,9 +82,10 @@ export const PhotoFilterBar: React.FC<PhotoFilterBarProps> = ({
             className="w-full md:w-auto text-sm md:text-base"
           >
             <span className="hidden md:inline">{t('common.sortBy')} </span>
-            {sortBy === 'date' ? t('gallery.sortByDate').replace('Sort by ', '') : 
-             sortBy === 'name' ? t('gallery.sortByName').replace('Sort by ', '') : 
+            {sortBy === 'date' ? t('gallery.sortByDate').replace('Sort by ', '') :
+             sortBy === 'name' ? t('gallery.sortByName').replace('Sort by ', '') :
              sortBy === 'size' ? t('gallery.sortBySize').replace('Sort by ', '') :
+             sortBy === 'capture_date' ? t('photoSort.dateTaken', 'Date Taken') :
              t('gallery.sortByRating', 'Rating')}
           </Button>
           
@@ -101,6 +102,17 @@ export const PhotoFilterBar: React.FC<PhotoFilterBarProps> = ({
               >
                 {t('gallery.sortByDate')}
               </button>
+              <button
+                onClick={() => {
+                  onSortChange('capture_date');
+                  setShowSortMenu(false);
+                }}
+                className={`w-full text-left px-4 py-2 text-sm hover:bg-black/10 ${
+                  sortBy === 'capture_date' ? 'text-primary-600 bg-primary-50' : 'text-muted-theme'
+                }`}
+              >
+                {t('photoSort.dateTaken', 'Date Taken')}
+              </button>
               <button
                 onClick={() => {
                   onSortChange('name');