feat: upgrade to v4.0 with complete English rewrite

- Update flowmaster.md from v1.0 to v4.0 (Product Evolution Studio)
  - Dual-mode: Analyze (v3.1) + Studio (v4.0)
  - Interactive canvas with terminal, voice comments, screenshots, git sync
  - Auto-layout algorithm with guaranteed zero-overlap spacing
  - Self-healing execution loop (generate, verify, fix, repeat)
- Rewrite README.md in English with badges, architecture diagram, examples
- Add MIT LICENSE
- Add CONTRIBUTING.md with guidelines