docs(person): ADR-039, DB diagrams, and V76 deploy runbook note

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/DEPLOYMENT.md

@@ -518,6 +518,26 @@ docker exec -i archive-db psql -U ${POSTGRES_USER} ${POSTGRES_DB} < backup-YYYYM
 
 Automated backup (nightly `pg_dump` + MinIO `mc mirror` over Tailscale to `heim-nas`) is a follow-up issue. Until that ships: **manual backups are the only recovery option.**
 
+### Deploy note — V76 (persons birth/death → date + precision, #773)
+
+V76 drops `persons.birth_year`/`death_year` after backfilling the new
+`birth_date`/`death_date` + precision columns — a **one-way migration** (Flyway cannot
+roll it back). Before deploying:
+
+1. Take a manual `pg_dump` (see above) — there is no automated nightly backup yet, so
+   confirm the dump completed before starting the deploy.
+2. No maintenance window is required: the pre-check + DDL run in one atomic Flyway
+   transaction, and this single-writer archive has no concurrent importers during deploy.
+
+If post-deploy data issues are found, restore **only the persons table** from the
+pre-migration dump (targeted restore, not a full-database restore):
+
+```bash
+pg_restore -t persons -d ${POSTGRES_DB} backup-YYYYMMDD.dump
+```
+
+(For a plain-SQL dump, extract the persons COPY block instead of replaying the full file.)
+
 ### Rollback
 
 Each release tag corresponds to a docker image tag on the host daemon (built via DooD; no registry). Rolling back to a previous tag is one command: