fix(duplicates): hoist memo hooks above early returns

Rules-of-hooks violation: useRef and three useCallbacks sat after the
isLoading/isError/empty early-return block, so first render (loading)
called N hooks and the post-data render called N+4, crashing the view.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/duplicates/DuplicatesView.tsx

@@ -180,6 +180,26 @@ export function DuplicatesView() {
     return () => window.removeEventListener('keydown', onKeyDown)
   }, [allMemberIds, activePhotoId, columns, selectPhoto, virtualizer])
 
+  // Stable handlers — passed through memoised section + thumbnail so
+  // React.memo is actually effective. The `discardMutation.mutate` and
+  // store actions have stable identity already; we wrap them once so the
+  // closure identity doesn't change per render. Must sit above the early
+  // returns below — rules of hooks forbid conditional hook calls.
+  const allMemberIdsRef = useRef(allMemberIds)
+  allMemberIdsRef.current = allMemberIds
+  const handleKeepBest = useCallback(
+    (discardIds: string[]) => discardMutation.mutate(discardIds),
+    [discardMutation]
+  )
+  const handlePreviewMember = useCallback(
+    (memberId: string) => openPreview(memberId, allMemberIdsRef.current),
+    [openPreview]
+  )
+  const handleSelectMember = useCallback(
+    (memberId: string) => selectPhoto(memberId),
+    [selectPhoto]
+  )
+
   if (isLoading) {
     return (
       <div className="flex h-full items-center justify-center text-text-muted">
@@ -211,25 +231,6 @@ export function DuplicatesView() {
     )
   }
 
-  // Stable handlers — passed through memoised section + thumbnail so
-  // React.memo is actually effective. The `discardMutation.mutate` and
-  // store actions have stable identity already; we wrap them once so the
-  // closure identity doesn't change per render.
-  const allMemberIdsRef = useRef(allMemberIds)
-  allMemberIdsRef.current = allMemberIds
-  const handleKeepBest = useCallback(
-    (discardIds: string[]) => discardMutation.mutate(discardIds),
-    [discardMutation]
-  )
-  const handlePreviewMember = useCallback(
-    (memberId: string) => openPreview(memberId, allMemberIdsRef.current),
-    [openPreview]
-  )
-  const handleSelectMember = useCallback(
-    (memberId: string) => selectPhoto(memberId),
-    [selectPhoto]
-  )
-
   return (
     <div ref={scrollRef} className="h-full overflow-auto bg-bg p-4 pb-20">
       <div className="mb-4 flex items-center gap-2 text-xs text-text-muted">