Switchyard Coding-Agent Launchers

Overview

CLI launchers are thin shells over profile-backed SwitchyardApp values:

• Single-model launches build a passthrough profile with build_tier_passthrough_switchyard(...).
• Multi-route launches load routing-profile YAML with load_route_bundle_table(...), which returns a RouteTable.
• The FastAPI app receives either a single profile-backed runtime or a RouteTable and serves it through build_switchyard_app(...).

Do not reintroduce SwitchyardRecipes, factory registries, middleware bundles, or request/response pipeline wrappers in launcher code.

--routing-profiles is a global switchyard flag before the subcommand. --model stays on the launcher subcommand. They are mutually exclusive for the launcher entry points that need a single initial model.