KTD1 second step (behavior preserved):
- squad defines ProgressSink (EmitPhase/Detail/Deliverable/Summary/Briefing)
with its own DetailEvent/ToolEvent types; zero internal/stream imports left
- bizdev assembly maps port to SSE streamer (squad_progress_adapter) and
injects via ctx at the four squad entry points
- process_bridge tests rewritten as port-contract tests (captureSink)
- verified: build+vet clean, squad/bizdev/archtest green
