feat(server): support read all notifications (#13083)

close AF-2719



#### PR Dependency Tree


* **PR #13083** 👈

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 the ability to mark all notifications as read with a single
action.
  
* **Bug Fixes**
  * Ensured notifications marked as read are no longer shown as unread.

* **Tests**
* Introduced new tests to verify the functionality of marking all
notifications as read.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -261,6 +261,18 @@ export class NotificationModel extends BaseModel {
     });
   }
 
+  async markAllAsRead(userId: string) {
+    const { count } = await this.db.notification.updateMany({
+      where: { userId },
+      data: {
+        read: true,
+      },
+    });
+    this.logger.log(
+      `Marked all notifications as read for user ${userId}, count: ${count}`
+    );
+  }
+
   /**
    * Find many notifications by user id, exclude read notifications by default
    */