Why: the migration recovery data lived only on the migration workstation;
before the local backup bundles are retired, the maps belong in the
process repo per the single-source rule.
Evidence: combined from backups-2026-09-30/mapping-*.txt (10 repos + parent
+ restored chains); migration record pointer updated.
Impact: record-only; enables the scheduled local backup cleanup while
remote archive refs remain the full safety net.
Refs: 2026-09-30-history-migration.md
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