Render QR code on finished series page; v2.0.34

The downloadQrUrl field was saved but never displayed — add the QR image
below the action buttons, wrapped in a link to the download URL.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/App.css

@@ -9919,6 +9919,30 @@
   transform: translateY(-1px);
 }
 
+.finished-series-qr {
+  margin-top: 1.25rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.35rem;
+  width: fit-content;
+}
+
+.finished-series-qr-img {
+  width: 100px;
+  height: 100px;
+  border-radius: 6px;
+  border: 1px solid rgba(201, 168, 76, 0.25);
+  display: block;
+}
+
+.finished-series-qr-label {
+  font-size: 0.72rem;
+  color: var(--brand-muted);
+  letter-spacing: 0.04em;
+  text-align: center;
+  margin: 0;
+}
+
 /* ── Download badge on grid cards ── */
 .finished-book-card-img-wrap {
   position: relative;