feat(server): impl doc gc (#15282)

#### PR Dependency Tree


* **PR #15282** 👈

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 document cleanup to reconcile missing workspace docs,
delete related stored data, and recover if the doc returns.
* Added effect-based follow-up reconciliation for search indexing,
Copilot embeddings, and comment attachment cleanup with explicit
acknowledgements.
* **Bug Fixes**
* Deleted-document references now persist as dangling references rather
than disappearing.
* Improved document deletion flow to enforce permissions and ensure
authorized deletions succeed.
* **Tests**
* Expanded coverage for cleanup recovery, indexing/embedding
reconciliation, permissions, and reference semantics.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/indexer/service.ts

@@ -374,14 +374,6 @@ export class IndexerService {
     );
 
     await this.deleteBlocksByDocId(workspaceId, docId, options);
-    await this.queue.add('copilot.session.deleteDoc', {
-      workspaceId,
-      docId,
-    });
-    await this.queue.add('copilot.embedding.deleteDoc', {
-      workspaceId,
-      docId,
-    });
     this.logger.log(`deleted doc ${workspaceId}/${docId}`);
   }