Documents the project-wide rule that Red Bear OS local forks are the
complete, authoritative source of truth for every component they cover.
Key points:
- A fork that delegates to upstream/crates.io is not a fork — it's a wrapper.
- Missing fork functionality is implemented in the fork, not papered over.
- Path deps + [patch.crates-io] everywhere; no version strings for forks.
- Adapt to upstream at the same pace — never pin back.
Adds a cross-reference from local/AGENTS.md DESIGN PRINCIPLE section.
