finalRecallRound native disabling

Chose protocol-native disabling of only recall on finalRecallRound over cached-tool mutation or prose because cache bytes must remain stable and models may ignore instructions. GatewayRequest.disableRecall is internal: parsers never accept it, ordinary builders never forward it, and only the final follow-up sets it. Filter recall for Anthropic, OpenAI Chat, and Gemini; native Responses retains cached definitions but synthesizes allowed_tools without recall. Sanitize contradictory tool_choice, preserve ordinary tools, and reject any recall still emitted. Capture mustFinalizeNext() once through setup/retries; recompute only after a validated nested recall advances the budget.