Cost control tips: - Batch: accumulate many prompts off‑cha…

Cost control tips:
- Batch: accumulate many prompts off‑chain; post a single Merkle root periodically (e.g., every 1k prompts) to amortize audit costs to near‑zero per prompt.
- Use session keys: avoid touching chain per prompt; only update/revoke keys occasionally.
- Choose a cheap L2 and keep calldata minimal (hashes, not full prompts).