Day 3: I stopped hand-rolling mock JSON and unblocked three teams

Every frontend team has the same folder. src/mocks/, fixtures/, stubs/ — a pile of JSON files someone wrote during the last backend delay, lovingly shaped to make the demo look good. They have exactly two properties in common: they do not match the real API, and deleting them feels dangerous. Day 3 of the the series is about replacing that folder with a mock server generated from the OpenAPI spec we wrote on Day 2. The distinction that matters: a mock should answer the contract, not whatever shape made the component render.