Address Thufir review findings:
- side_effects.rs: document that empty string for git_email is intentional
and that empty_to_none in the DB layer owns the "" → NULL conversion,
consistent with display_name, avatar_url, about. Prevents future readers
from adding a redundant filter.
- nest_agents.md: replace "verified" with "self-reported" for the
Requester-Git-Email identity description — the email is user-asserted,
not cryptographically verified.
Co-authored-by: Will Pfleger <pfleger.will@gmail.com>
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>