Model watch2026-10-184 min Grok 4.7 API Guide: 500K Context, $2/$6 Pricing, and xhigh ReasoningxAI released Grok 4.7 on Sept 21, 2026. Model ID, two price tiers split at 200K tokens, how to pick a reasoning effort, and a curl example. #Grok#xAI#API pricing#reasoning effort