feat(server): blob reconciliation (#15165)

#### PR Dependency Tree


* **PR #15165** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added automated backend maintenance for missing blob metadata
backfill, document-to-blob reference rebuilding, and unreferenced blob
cleanup planning/execution.
* Introduced scheduled batch processing (workspace-paged) and paginated
object-storage listing.
* **Bug Fixes**
* Improved reliability of object-storage reads by treating expected “not
found” results as non-errors.
* Strengthened blob/expired cleanup flows with runtime-driven batching
and reduced coupling to metadata synchronization.
* **Tests**
* Expanded unit and e2e coverage for partial blob metadata and updated
runtime/job cleanup test assertions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/models/blob.ts

@@ -96,32 +96,6 @@ export class BlobModel extends BaseModel {
     return count > 0;
   }
 
-  async listPendingExpired(before: Date) {
-    return await this.db.blob.findMany({
-      where: {
-        status: 'pending',
-        deletedAt: null,
-        createdAt: {
-          lt: before,
-        },
-      },
-      select: {
-        workspaceId: true,
-        key: true,
-        uploadId: true,
-      },
-    });
-  }
-
-  async listDeleted(workspaceId: string) {
-    return await this.db.blob.findMany({
-      where: {
-        workspaceId,
-        deletedAt: { not: null },
-      },
-    });
-  }
-
   async totalSize(workspaceId: string) {
     const sum = await this.db.blob.aggregate({
       where: {