agent-shell 0.63 updates

It hasn't been long since the 0.55 update, but plenty has landed since. Let's go through the highlights as of v0.63. What's agent-shell? agent-shell is a native Emacs mode to interact with AI agents powered by ACP (Agent Client Protocol). Supported agents The roster keeps growing. This cycle adds two new agents: Grok Build (xAI), #720 by @eddof13. Oh My Pi (omp), #631 by @tychoish. Additionally: Cursor now runs on the official Cursor CLI (agent acp). Note a recent CLI is required, as the acp subcommand was only added in 2026. Codex now uses @agentclientprotocol/codex-acp. Cline now accepts a default model and session mode via defcustoms (#693 by @nhojb). Goose no longer requires an OpenAI key by default (#711 by @hoyon). Qwen now has explicit support for OpenAI-compatible keys. Custom markdown renderers The new markdown renderer introduced in 0.55 is now extensible. Third-party packages can claim and render specific markdown constructs (source blocks, inline code ranges, and more)…