- Adds SourceNode varchar(64) NULL to AuditLog, Notifications, and SiteCalls
tables with role-name semantics: node-a/node-b for site rows (qualified by
SourceSiteId), central-a/central-b for central direct-write rows.
- New IX_AuditLog_Node_Occurred (SourceNode, OccurredAtUtc) index.
- Reframes CLAUDE.md from documentation-only to implementation project.
- Adds docs/plans/2026-05-23-audit-source-node.md + tasks.json companion.