Document contributor attribution policy

[SynapseOpsAgent]

Summary

• Document that maintainer commits should use GitHub-linked author email for accurate contributor attribution.

Verification

• python3 tests/run_tests.py
• python3 -m py_compile scripts/route.py tests/run_tests.py
• scripts/github-preflight.sh
• targeted public leakage and credential scan

Security Notes

• Documentation-only change.
• No secrets or private infrastructure references added.
• This PR must be merged with a merge commit, not squash, so Trent Doney's authored commit remains in default-branch history for contributor attribution.