Get User Llm Usage Logs

List per-call LLM usage logs for a specific user, most recent first.

Each row records a single LLM call: provider, model, purpose (primary / vision / heartbeat / compaction / etc.), token counts, and cost in USD. Purpose lets you spot a runaway compaction loop or a heartbeat model burning cache misses.

The audit dependency writes one row when the route exits, matching the policy on the user-detail endpoint.