Expand AssetRegister and DataRegister with T0/T4 stack assets.
Add ResiliencePolicy, PanicSheet, full-server-loss runbook, and five
incident playbooks. Update README with mirror status. Mark T02-T05,
T07-T08 done; T01 and T06 in progress.
Add AssetRegister.yaml and DataRegister.yaml documenting the
railiance-backup tool family, backup lanes, data classes, gaps,
and RTO/RPO targets. Mark T01 done.