CLI command surface listing for agents, in JSON and toon

The CLI now exposes a --list flag on the global command and on subcommands, so agents can discover the available command surface programmatically. Output is emitted in JSON or toon formats, and a separate init --list path returns the same machine-readable description for the init workflow. This makes it practical for coding agents to introspect what once can do without parsing prose or guessing subcommand paths.