feat: per-photo permanent delete + discarded thumbnail treatment

Discarded photos now look discarded in the grid (50% opacity + grayscale)
with a red trash badge in the corner instead of a bare icon. The discard
action bar gains a "Delete N" button that permanently deletes only the
current selection, complementing the existing "Empty discard pile".

Backend: new DELETE /discard endpoint accepting {photo_ids: [...]} that
permanently removes only listed photos. Skips ids that aren't in the
discard pile so it can never bypass the soft-delete safety net.

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

frontend/src/components/discard/DiscardActionBar.tsx

@@ -21,6 +21,7 @@ export function DiscardActionBar() {
   const { data: photos = [] } = usePhotosQuery()
 
   const [confirmOpen, setConfirmOpen] = useState(false)
+  const [deleteSelectedOpen, setDeleteSelectedOpen] = useState(false)
 
   const restoreMutation = useMutation({
     mutationFn: (ids: string[]) => discardApi.restore(ids),
@@ -32,6 +33,30 @@ export function DiscardActionBar() {
     onError: (e: any) => toast.error('Restore failed', e.message || 'Unknown error'),
   })
 
+  const deleteSelectedMutation = useMutation({
+    mutationFn: (ids: string[]) => discardApi.deletePermanent(ids),
+    onSuccess: (data: any) => {
+      const count = data?.deleted ?? 0
+      const errors = data?.file_errors ?? 0
+      if (errors > 0) {
+        toast.error(
+          `Deleted with ${errors} error${errors > 1 ? 's' : ''}`,
+          `${count} record${count === 1 ? '' : 's'} deleted; some files could not be removed`
+        )
+      } else {
+        toast.success(
+          'Permanently deleted',
+          `${count} photo${count === 1 ? '' : 's'} removed from disk`
+        )
+      }
+      clearSelection()
+      queryClient.invalidateQueries({ queryKey: ['photos'] })
+      setDeleteSelectedOpen(false)
+    },
+    onError: (e: any) =>
+      toast.error('Delete failed', e.message || 'Unknown error'),
+  })
+
   const emptyMutation = useMutation({
     mutationFn: () => discardApi.empty(),
     onSuccess: (data: any) => {
@@ -70,15 +95,26 @@ export function DiscardActionBar() {
 
         <div className="flex items-center gap-2">
           {selected > 0 && (
-            <button
-              onClick={() => restoreMutation.mutate(selectedPhotos)}
-              disabled={restoreMutation.isPending}
-              className="flex items-center gap-1.5 rounded bg-surface-2 px-3 py-1 text-text hover:bg-surface-offset disabled:opacity-50"
-              title="Restore selected (U)"
-            >
-              <RotateCcw className="h-3.5 w-3.5" />
-              Restore {selected}
-            </button>
+            <>
+              <button
+                onClick={() => restoreMutation.mutate(selectedPhotos)}
+                disabled={restoreMutation.isPending}
+                className="flex items-center gap-1.5 rounded bg-surface-2 px-3 py-1 text-text hover:bg-surface-offset disabled:opacity-50"
+                title="Restore selected (U)"
+              >
+                <RotateCcw className="h-3.5 w-3.5" />
+                Restore {selected}
+              </button>
+              <button
+                onClick={() => setDeleteSelectedOpen(true)}
+                disabled={deleteSelectedMutation.isPending}
+                className="flex items-center gap-1.5 rounded bg-reject/20 px-3 py-1 text-reject hover:bg-reject/30 disabled:opacity-50"
+                title="Permanently delete selected"
+              >
+                <Trash2 className="h-3.5 w-3.5" />
+                Delete {selected}
+              </button>
+            </>
           )}
           <button
             onClick={() => setConfirmOpen(true)}
@@ -92,6 +128,22 @@ export function DiscardActionBar() {
         </div>
       </div>
 
+      <ConfirmDialog
+        isOpen={deleteSelectedOpen}
+        title={`Delete ${selected} photo${selected === 1 ? '' : 's'}?`}
+        message={
+          <>
+            This will <strong className="text-text">permanently delete</strong>{' '}
+            {selected} photo{selected === 1 ? '' : 's'} and remove the file
+            {selected === 1 ? '' : 's'} from disk. This cannot be undone.
+          </>
+        }
+        confirmLabel="Delete"
+        destructive
+        onConfirm={() => deleteSelectedMutation.mutate(selectedPhotos)}
+        onClose={() => setDeleteSelectedOpen(false)}
+      />
+
       <ConfirmDialog
         isOpen={confirmOpen}
         title="Empty discard pile?"