feat(worker): CRC32 archive fingerprint compare

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/src/archive/fingerprint.ts

@@ -0,0 +1,21 @@
+import type { FileEntry } from "./zip-reader.js";
+
+export function crcFingerprint(entries: FileEntry[]): { crcs: string[]; complete: boolean } {
+  if (entries.length === 0) return { crcs: [], complete: false };
+  const crcs: string[] = [];
+  let complete = true;
+  for (const e of entries) {
+    if (e.crc32 == null) { complete = false; continue; }
+    crcs.push(e.crc32.toLowerCase());
+  }
+  crcs.sort();
+  return { crcs, complete };
+}
+
+export function fingerprintsMatch(a: FileEntry[], b: FileEntry[]): boolean {
+  const fa = crcFingerprint(a);
+  const fb = crcFingerprint(b);
+  if (!fa.complete || !fb.complete) return false;
+  if (fa.crcs.length !== fb.crcs.length) return false;
+  return fa.crcs.every((c, i) => c === fb.crcs[i]);
+}