Adds audit log entries for all write endpoints in routes_organizations.py
(ORG_CREATE, ORG_UPDATE, ORG_MEMBER_ADD, ORG_MEMBER_UPDATE, ORG_MEMBER_REMOVE)
and routes_invitations.py (INVITATION_CREATE, INVITATION_REVOKE, INVITATION_ACCEPT).
The public accept endpoint passes user=None per the no-auth contract.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>