feat(server): add comment-attachment model (#12909)

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

* **New Features**
* Introduced support for comment attachments, allowing users to add,
view, and manage attachments linked to comments within documents.
* **Tests**
* Added comprehensive tests to ensure correct behavior for adding,
updating, deleting, listing, and retrieving comment attachments.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->


#### PR Dependency Tree


* **PR #12909** 👈
  * **PR #12911**
    * **PR #12761**
      * **PR #12924**
        * **PR #12925**

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

packages/backend/server/src/models/comment-attachment.ts

@@ -0,0 +1,70 @@
+import { Injectable } from '@nestjs/common';
+import { Prisma } from '@prisma/client';
+
+import { BaseModel } from './base';
+
+export type CreateCommentAttachmentInput =
+  Prisma.CommentAttachmentUncheckedCreateInput;
+
+/**
+ * Comment Attachment Model
+ */
+@Injectable()
+export class CommentAttachmentModel extends BaseModel {
+  async upsert(input: CreateCommentAttachmentInput) {
+    return await this.db.commentAttachment.upsert({
+      where: {
+        workspaceId_docId_key: {
+          workspaceId: input.workspaceId,
+          docId: input.docId,
+          key: input.key,
+        },
+      },
+      update: {
+        name: input.name,
+        mime: input.mime,
+        size: input.size,
+      },
+      create: {
+        workspaceId: input.workspaceId,
+        docId: input.docId,
+        key: input.key,
+        name: input.name,
+        mime: input.mime,
+        size: input.size,
+      },
+    });
+  }
+
+  async delete(workspaceId: string, docId: string, key: string) {
+    await this.db.commentAttachment.deleteMany({
+      where: {
+        workspaceId,
+        docId,
+        key,
+      },
+    });
+    this.logger.log(`deleted comment attachment ${workspaceId}/${key}`);
+  }
+
+  async get(workspaceId: string, docId: string, key: string) {
+    return await this.db.commentAttachment.findUnique({
+      where: {
+        workspaceId_docId_key: {
+          workspaceId,
+          docId,
+          key,
+        },
+      },
+    });
+  }
+
+  async list(workspaceId: string, docId?: string) {
+    return await this.db.commentAttachment.findMany({
+      where: {
+        workspaceId,
+        docId,
+      },
+    });
+  }
+}