Add host bootstrap and repair helpers

Add a dedicated pyro host surface for supported chat hosts so Claude Code, Codex, and OpenCode users can connect or repair the canonical MCP setup without hand-writing raw commands or config edits.

Implement the shared host helper layer and wire it through the CLI with connect, print-config, doctor, and repair, all generated from the same canonical pyro mcp serve command shape and project-source flags. Update the docs, public contract, examples, changelog, and roadmap so the helper flow becomes the primary onramp while raw host-specific commands remain as reference material.

Harden the verification path that this milestone exposed: temp git repos in tests now disable commit signing, socket-based port tests skip cleanly when the sandbox forbids those primitives, and make test still uses multiple cores by default but caps xdist workers to a stable value so make check stays fast and deterministic here.

Validation:
- uv lock
- UV_OFFLINE=1 UV_CACHE_DIR=.uv-cache make check
- UV_OFFLINE=1 UV_CACHE_DIR=.uv-cache make dist-check

docs/public-contract.md

@@ -94,6 +94,17 @@ Host-specific setup docs:
 - [opencode_mcp_config.json](../examples/opencode_mcp_config.json)
 - [mcp_client_config.md](../examples/mcp_client_config.md)
 
+The chat-host bootstrap helper surface is:
+
+- `pyro host connect claude-code`
+- `pyro host connect codex`
+- `pyro host print-config opencode`
+- `pyro host doctor`
+- `pyro host repair HOST`
+
+These helpers wrap the same `pyro mcp serve` entrypoint and are the preferred
+setup and repair path for supported hosts.
+
 ## Chat-Facing Workspace Contract
 
 `workspace-core` is the normal chat path. It exposes: