fix(profile): revoke CV-preview blob URLs on unmount, not on every change

The PDF-carousel cleanup effect had `[pdfCarousel]` deps, so its cleanup ran on
every carousel change and revoked the *previous* array's object URLs — which are
still referenced by unchanged items in the new array. Building a multi-template
deck therefore left every preview except the last with a revoked (broken) blob
URL. Drop paths are already handled explicitly in savePdfToCarousel (replace)
and resetPdfCarousel (clear), so blanket per-change revocation was both harmful
and redundant.

Fix: track the latest carousel in a ref and revoke outstanding URLs only on
unmount (empty-deps effect). No leak either way — unmount still frees them.

Found during the memory-leak/resource audit; this is a resource-release
correctness bug (over-eager revocation), not a leak. profile-page.test: 5/5
green (with an adequate timeout; the suite's 5s-timeout flakiness is pre-existing
and unrelated).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

job-tracker-ui/src/pages/ProfilePage.tsx

@@ -267,15 +267,27 @@ export default function ProfilePage() {
   const [currentPassword, setCurrentPassword] = useState("");
   const [newPassword, setNewPassword] = useState("");
 
+  // Keep a ref to the latest carousel so the unmount cleanup can revoke the
+  // outstanding preview object URLs without re-running on every change.
+  const pdfCarouselRef = useRef<PdfCarouselItem[]>([]);
   useEffect(() => {
+    pdfCarouselRef.current = pdfCarousel;
+  }, [pdfCarousel]);
+
+  useEffect(() => {
+    // Revoke any remaining preview object URLs only on unmount. Per-change
+    // revocation is already handled explicitly in savePdfToCarousel (replace) and
+    // resetPdfCarousel (clear); doing it here on every pdfCarousel change revoked
+    // URLs that were still referenced by other items in the deck, breaking their
+    // previews.
     return () => {
-      pdfCarousel.forEach((item) => {
+      pdfCarouselRef.current.forEach((item) => {
         if (item.pdfUrl) {
           window.URL.revokeObjectURL(item.pdfUrl);
         }
       });
     };
-  }, [pdfCarousel]);
+  }, []);
 
   const loadProfile = useCallback(async () => {
     setLoading(true);