Expand a one-line feature description into a complete production-quality vertical slice — all 11 filled docs (persona, journey, UI, API, DB, security, observability, AI, seed, tests, index) plus migrations, seed TypeScript, Gherkin features, and OpenAPI fragment. Use when the user invokes /slice <de
Expand a one-line feature description into a complete production-quality vertical slice — all 11 filled docs (persona, journey, UI, API, DB, security, observability, AI, seed, tests, index) plus migrations, seed TypeScript, Gherkin features, and OpenAPI fragment. Use when the user invokes /slice <description>, or says "build a full slice", "create a vertical slice", or wants a shippable persona→jo