fix(backup): keep a wipe's purge request until the next off-host run

A data wipe during the nightly upload could leave the pre-wipe copy in
the bucket: the purge the wipe started removed its request at once, and
the upload still in flight checked that request after finishing and found
nothing. A wipe's request now stays until a nightly run has walked the
account since the wipe. Until then each purge removes only the copies
dated up to the wipe's day, so the copy of what the account holds after
the wipe stays, and the admin card no longer counts the waiting request
as copies still in the bucket.

src/app/api/admin/backups/route.ts

@@ -167,9 +167,20 @@ export const GET = apiHandler(async () => {
       a.username.localeCompare(b.username),
   );
 
+  // A wipe whose copies are already gone waits for the next nightly run
+  // before its request is removed (see `offhost-purge.ts`); nothing of it is
+  // left in the bucket, so it is not counted as a pending deletion.
+  const stillInBucket = {
+    NOT: {
+      reason: "data_wiped",
+      lastFailure: null,
+      lastAttemptAt: { not: null },
+    },
+  };
   const [purgeCount, oldestPurge, lifecycle] = await Promise.all([
-    prisma.offhostPurgeRequest.count(),
+    prisma.offhostPurgeRequest.count({ where: stillInBucket }),
     prisma.offhostPurgeRequest.findFirst({
+      where: stillInBucket,
       orderBy: { requestedAt: "asc" },
       select: { requestedAt: true, lastFailure: true },
     }),