release: v1.2.0 Production GA (single-node)

- known-limitations, deployment runbook, release checklist
- prod compose requires JWT secret; BARADB_ENV=production fail-closed
- scripts/backup-restore-drill.sh (backup → wipe → restore → verify)
- version bump 1.2.0 (nimble, Dockerfile, health, CHANGELOG dated)

docs/en/known-limitations.md

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+# Known Limitations — v1.2.0 Production GA
+
+This page defines **what BaraDB promises** in the v1.2.0 production cut.
+
+| Tier | Meaning |
+|------|---------|
+| **Supported (GA)** | Documented, tested, appropriate for production apps that fit the scope |
+| **Experimental** | Works in tests/ops demos; not a reliability SLA target |
+| **Not supported** | Out of scope; may fail or corrupt assumptions |
+
+## Support matrix
+
+| Area | GA (v1.2.0) | Experimental / later |
+|------|-------------|----------------------|
+| Single-node SQL + LSM storage | **Supported** | — |
+| Schema persistence (tables, indexes) | **Supported** | — |
+| FTS / HNSW / graphs across restart | **Supported** | — |
+| Auth + JWT (when configured) | **Supported** | — |
+| Backup / restore (offline, all-databases) | **Supported** | — |
+| Multi-database (non-Raft) | **Supported** | — |
+| Raft 3-node election + SQL/DDL | **Experimental** | InstallSnapshot SM payload, membership |
+| Raft multi-database | **Not supported** | only `default` |
+| Leader write forwarding | **Experimental** | needs `BARADB_RAFT_CLIENT_PEERS` |
+| Follower linearizable reads | **Not supported** | best-effort after apply |
+| ORC multi-threaded shared LSM | **Not supported** | default is ARC (`nim.cfg`) |
+| Zero-downtime rolling upgrade | **Not supported** | stop → backup → upgrade |
+| Postgres wire protocol | **Not supported** | Bara wire + HTTP |
+
+## Single-node GA (what you can rely on)
+
+- Process crash + WAL recovery for the default durability settings
+- CREATE TABLE / indexes that survive restart (see engine-persistence work)
+- HTTP `/health` and `/metrics` for process liveness
+- Offline backup of `data/databases` and restore onto an empty data root
+
+## Raft (experimental ops)
+
+Documented in [distributed.md](distributed.md). Suitable for learning and careful staging; **not** the v1.2.0 HA product tier.
+
+- SQL DML/DDL on **`default` only**
+- Safe log prefix compact (not full InstallSnapshot)
+- Failover proven in process e2e tests
+
+## Operational requirements
+
+- Set a strong `BARADB_JWT_SECRET` and `BARADB_AUTH_ENABLED=true` in production (see prod compose)
+- Test restores regularly (`scripts/backup-restore-drill.sh`)
+- Do not share one data directory between two running processes
+
+## See also
+
+- [Deployment / runbook](deployment.md)
+- [Backup](backup.md)
+- [Raft cluster status](../superpowers/specs/2026-07-30-raft-cluster-status.md)
+- [Production GA plan](../superpowers/plans/2026-07-30-production-ga.md)