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/app.module.ts

@@ -30,6 +30,7 @@ import { RateLimiterModule } from './base/throttler';
 import { WebSocketModule } from './base/websocket';
 import { AccessTokenModule } from './core/access-token';
 import { AuthModule } from './core/auth';
+import { BackendRuntimeModule } from './core/backend-runtime';
 import { CommentModule } from './core/comment';
 import { ServerConfigModule, ServerConfigResolverModule } from './core/config';
 import { DocStorageModule } from './core/doc';
@@ -120,6 +121,7 @@ export const FunctionalityModules = [
   JobModule.forRoot(),
   RealtimeModule,
   ModelsModule,
+  BackendRuntimeModule,
   ScheduleModule.forRoot(),
   MonitorModule,
 ];