Google Antigravity (agy CLI) models for DeepSeek Harness — streaming chat, thinking, tool activity, usage, in-GUI Google OAuth login

DeepSeek Harness coding-subscription OAuth: SuperGrok/Grok Build, ChatGPT Plus Codex, Kimi Code, Claude Code. Fixes AUTH API key is invalid, INVALID_REPLAY_STATE, grok-4.6 xhigh, Kimi Bearer vs x-api-key.