xiaoju
892ccab8d5
feat(uwf-agent-kit): frontmatter fast path + prompt injection
Port RFC #351 frontmatter markdown to uwf-* path:
- tryFrontmatterFastPath(): parse → validate → JSON Schema check via json-cas
- Happy path skips LLM extract, fallback to existing extract()
- buildOutputFormatInstruction(): generates deliverable format from JSON Schema
- Injected into agent context before execution
- Scope reminder: 'Focus exclusively on YOUR role's deliverable'
- 14 new tests (vitest)
Closes #355