Add ACP Support

Feature Description

Command Code currently integrates with editors via MCP or headless mode(cmd -p --output-format json), but it cannot be embedded as an agent in editors/IDEs that speak the Agent Client Protocol (ACP). ACP is becoming the de-facto standard for editor–agent communication and is already supported by Zed, JetBrains IDEs, and Typstify, with adapters for Claude Code, Codex, OpenCode, and Cline.

Use Case

I write Typst documents in Typstify, whose v1.8.0 AI Assistant launches any ACP agent and augments it with editor-aware MCP tools: getActiveDocument, getDocumentOutline, queryDiagnostics, typstCompiler (PDF/PNG/SVG export), previewer control, and TPIX package search/download. Configuring Command Code as the agent would let me use its models, taste learning, skills, and plan mode directly inside the editor - with permission approvals in the UI and sessions I can resume - instead of switching to a terminal for every task.

Additional Context

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How important is this to you?

Blocking adoption or production use

首先定位现有的 MCP 和 headless 集成，然后检查 ACP 对编辑器与 agent 通信的要求。当 Command Code 能够由兼容 ACP 的编辑器启动，并支持所请求的 agent 交互、权限批准和可恢复会话时，即可视为完成。