fix(library): resolve main-thread UI freeze and process kill data loss via OPFS payload capping, yield throttling, and UI batching

docker/frontend/src/Library.tsx

@@ -469,19 +469,32 @@ export function Library() {
         fresh = 0;
       }
     };
-    // The reading hands its frames over the moment their batch is stored, so the
-    // strip is the roll arriving rather than the roll being found again — a read
-    // of the whole catalogue costs every thumbnail in it, and on a folder of RAW
-    // that read beside a quarter of a gigabyte of decoder is what took the tab.
+    let pendingRows: LibraryPhoto[] = [];
+    let updateTimer: ReturnType<typeof setTimeout> | null = null;
+
+    const flushPending = () => {
+      if (pendingRows.length > 0) {
+        const toAdd = pendingRows;
+        pendingRows = [];
+        setPhotos((prev) => [...prev, ...toAdd]);
+      }
+      updateTimer = null;
+    };
+
     watchRows((rows) => {
       fresh += rows.length;
-      setPhotos((prev) => [...prev, ...rows]);
+      pendingRows.push(...rows);
+      if (!updateTimer) {
+        updateTimer = setTimeout(flushPending, 500);
+      }
     });
     const unwatch = watchScan(watching);
     // A scan already in flight when this screen opens is picked up where it is:
     // the reader who left for the studio comes back to the same roll.
     watching();
     return () => {
+      if (updateTimer) clearTimeout(updateTimer);
+      flushPending();
       unwatch();
       watchRows(null);
     };