§1 worked example rewritten to direct factory injection (no container
rebinding). §4 mocking decision tree updated. New §sections for R25
output-validation tests, R26 router error-mapping tests, R27/R28
presenter-shape tests. §9 contract-suite paths use the post-Plan-8
.mock.ts suffix.
Refactor log doc-update checklist: tdd-workflow.md ticked.