feat(server): add comment-attachment storage (#12911)

close CLOUD-230












#### PR Dependency Tree


* **PR #12911** 👈
  * **PR #12761**
    * **PR #12924**
      * **PR #12925**

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 support for uploading and retrieving comment attachments in
workspace documents via a new API endpoint.
* Introduced a service for managing comment attachments, including
storage, retrieval, deletion, and URL generation.
* Implemented localized error messages and improved error handling for
missing comment attachments.

* **Bug Fixes**
  * Improved error feedback when comment attachments are not found.

* **Tests**
* Added comprehensive tests for comment attachment storage, retrieval,
deletion, API endpoint behavior, and permission checks.

* **Documentation**
* Updated GraphQL schema and localization files to include new error
types for comment attachments.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/base/error/def.ts

@@ -917,4 +917,8 @@ export const USER_FRIENDLY_ERRORS = {
     type: 'resource_not_found',
     message: 'Reply not found.',
   },
+  comment_attachment_not_found: {
+    type: 'resource_not_found',
+    message: 'Comment attachment not found.',
+  },
 } satisfies Record<string, UserFriendlyErrorOptions>;