Add META topic, CONSUMERS.md, and refine ADR/Framework rules
- Introduced META topic with META_ISSUES.md and META_TODO.md for protocol meta-tooling tracking.
- Updated TOPIC_CODES.md to register META topic.
- Added CONSUMERS.md to document consumer repos per Framework-First exception.
- Extended Framework-First rule to all docs, documenting the CONSUMERS.md exception.
- Refined adr-author skill: explicit ADR keyword triggers, complexity-based ask-back, and clarified non-trigger cases.
- Improves meta-tooling governance, cross-layer doc boundaries, and ADR process.
