Admin controls to purge only attachments or attachments above a size threshold

Problem

Large media attachments accumulate in storage over time, increasing hosting costs and making maintenance harder. Operators need a safe, targeted tool to clean up attachments and free space on the server.

Proposal

Add an admin-only tool to identify and purge media attachments from storage with the following capabilities:

• Scope selection: all attachments, attachments for a specific user by user id or prefix, or a custom prefix.
• Size threshold: option to purge only attachments larger than a configurable size in MB.
• Dry run mode: list candidate objects and estimated count/size without executing the purge.
• API endpoint and background job to perform batched purges to avoid load spikes.