Example tasks

Example tasks that needs to be easily done:
- List all comments containing "Test" and delete them
- Move all comments from topic X to topic Y
- List all comments by user A
- List all users close to the storage limit

No files, tests, or entry points are named. Start by finding the admin entry points for comments, users, topics, and storage limits, then clarify the intended behavior for each listed task. Done means the four requested operations are available and their expected results are verified.

Written by the indexing model from the issue text.