Analyze the architecture of a code repository — component structure, layering, data flow, dependency direction, and cross-cutting concerns. Run independently whenever someone wants to understand how a codebase is structured, needs an architecture diagram, or wants to review architectural patterns. Requires a survey (run repo-surveyor first if `survey.md` doesn't exist). Writes `architecture.md` and a manifest sidecar so repo-analyst can detect when this lens needs refresh.
