feat: editable taken_at + folder-based date repair and filter

Lets operators fix corrupted capture dates at scale. Adds an editable
Date Taken field with a folder/filename-derived suggestion hint, a bulk
Date Taken section in the multi-select sidebar that either applies one
date to the whole selection or infers a per-photo date from each path,
a warning badge on thumbnails whose stored date disagrees with the
path, and a "Date issues" filter pill so suspicious photos can be
surfaced and fixed as a group. Edits are written back to EXIF on disk
so rescans don't clobber the fix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/hooks/useFilterUrlSync.ts

@@ -89,6 +89,7 @@ function parseUrl(): HydratePayload {
   }
 
   if (sp.get('duplicates') === 'true') out.duplicates = true
+  if (sp.get('date_warning') === 'true') out.dateWarning = true
 
   const groupBy = sp.get('group')
   if (groupBy === 'date' || groupBy === 'tag') out.groupBy = groupBy
@@ -123,6 +124,7 @@ function writeUrl(f: FilterState & { currentSection?: string }) {
   if (f.folderId) sp.set('folder_id', f.folderId)
   if (f.tagIds.length > 0) sp.set('tag_ids', f.tagIds.join(','))
   if (f.duplicates) sp.set('duplicates', 'true')
+  if (f.dateWarning) sp.set('date_warning', 'true')
   if (f.groupBy !== 'date') sp.set('group', f.groupBy)
   if (f.currentSection && f.currentSection !== 'all-photos')
     sp.set('section', f.currentSection)

frontend/src/hooks/usePhotosQuery.ts

@@ -39,6 +39,7 @@ export function usePhotosQuery() {
   const folderId = useFilterStore((s) => s.folderId)
   const tagIds = useFilterStore((s) => s.tagIds)
   const duplicates = useFilterStore((s) => s.duplicates)
+  const dateWarning = useFilterStore((s) => s.dateWarning)
   const groupBy = useFilterStore((s) => s.groupBy)
   const sortBy = useFilterStore((s) => s.sortBy)
   const sortOrder = useFilterStore((s) => s.sortOrder)
@@ -58,11 +59,12 @@ export function usePhotosQuery() {
         folderId,
         tagIds,
         duplicates,
+        dateWarning,
         groupBy,
         sortBy,
         sortOrder,
       }),
-    [q, dateFrom, dateTo, mediaTypes, ratingMin, ratingMax, colorLabel, flag, heapId, folderId, tagIds, duplicates, groupBy, sortBy, sortOrder]
+    [q, dateFrom, dateTo, mediaTypes, ratingMin, ratingMax, colorLabel, flag, heapId, folderId, tagIds, duplicates, dateWarning, groupBy, sortBy, sortOrder]
   )
 
   const queryClient = useQueryClient()