Delete EXPIRED ANONYMOUS TRIAL workspaces. Never a creator's.

🔴 THIS CRON MAY NOT DELETE OWNED WORKSPACES, AND CANNOT. Creator media is inventory: it is what x402 agents buy through media_search / purchase_metadata / purchase_content. A timer that deletes it destroys saleable stock and a creator's archive at once. Owned workspaces are permanent (decision 2026-09-01, workspace_routes.py:521); only anonymous "Try Now" sandboxes expire.

Two independent things keep that true, and only the second is load-bearing:

1. the query below filters owner_id == None, so an owned workspace is not even considered. This is an efficiency and a statement of intent.
2. _delete_trial_workspace_cascade RE-READS each document and RAISES on anything owned. This is the guarantee. Widening the query cannot widen what gets deleted.

A refusal is logged and counted, never swallowed: if this cron ever selects an owned workspace, that is a bug in the selection and the evidence must survive the run.

Scheduled daily; trials live TrialConfig.SESSION_DURATION_HOURS (72h), so a daily tick removes them within a day of expiry. Processes up to batch_size per invocation.