Move the complete research domain from docs/research to root-level research, update indexes and path-aware tooling, and align raw snapshot governance and CODEOWNERS.\n\nVerified with make test and GitHub CI.
- add local external resources registry
- add research domain contract and per-repository research domains
- add raw fact snapshot governance and validation scripts
Validation:
- make test
- git diff --check HEAD~1..HEAD
Note:
- welcome workflow failed because its action input names are stale; core content CI passed.