Creates the Source-of-Truth docs for a new mobile app idea (00-project-brief.md, 00-decisions.md, 00-glossary.md) from a short Idea Capsule. Use at the start of every new idea, before PRD/UX/architecture, or when the user asks for initial docs, a project brief, or to start a new idea. Do not do market research, TAM/SAM/SOM, or generate code.