Dsh Commandcode Provider

Key features

• It talks to Command Code's own streaming endpoint with the same wire protocol the official CLI uses (x-command-code-version, x-cli-environment, x-project-slug, … headers).
• Provider registration — registers the commandcode provider route on ctx.llm with the same /alpha/generate streaming protocol, retry/timeout/abort semantics, and message/tool conversion as the pi plugin (paired tool-call filtering, data-URL image forwarding, legacy schema normalization).
• The API key from Studio is an authentication credential for that endpoint — the same one cmd login writes to /.commandcode/auth.json.
• Because it rides the CLI protocol instead of the Provider API, it works on every plan, including Go, and even models the Provider API cannot serve.
• Model discovery still uses the public Provider API catalog endpoint when reachable, with an offline cache at /commandcode/commandcode-models.json