Replace one-shot grok -p JSON with native grok agent stdio (ACP) for realtime
streaming, tool visibility, and multi-turn sessions. Vendor the ACP client
into fusion-plugin-grok-runtime, forward Fusion fn_* tools and operator MCP,
stage Fusion skills via --plugin-dir, authenticate per xAI headless docs, and
align project chat manager store resolution so Grok chat sessions can send.