v0.7.0 — agent-sidecar rebrand + multi-agent docs

The plugin, MCP server, and canvas are all named agent-sidecar now. Install: /plugin marketplace add smarchetti/agent-sidecar then /plugin install agent-sidecar@agent-sidecar (existing installs of the old sidecar plugin: uninstall and reinstall). Docs now include setup for Cursor, VS Code, Codex CLI, Gemini CLI, and Windsurf — any MCP client can run bunx agent-sidecar. Technical identifiers (.sidecar/, SIDECAR_PORT, X-Sidecar-Token) are unchanged.