v3: type checking and lint pass clean — thumbnail placeholder takes file-dump props, no manual memo the compiler can't keep, no setState straight in effect bodies

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/components/DumpCreateModal.tsx

@@ -333,7 +333,8 @@ export function DumpCreateModal(
   const toggleCategory = (id: string) =>
     setSelectedCategoryIds((prev) => {
       const next = new Set(prev);
-      next.has(id) ? next.delete(id) : next.add(id);
+      if (next.has(id)) next.delete(id);
+      else next.add(id);
       return next;
     });