fix(db): version schema migrations

[KIDA-MNESIA]

Summary

• fix AR-H2 by recording immutable ordered schema migrations with exact checksums and replacing startup DDL with a read-only supported-version gate
• run one candidate-image migration Job before Deployment mutation, remove per-replica migration init containers, and leave the current ReplicaSet untouched on migration failure
• promote only when required indexes are valid, ready, and live; document expand/contract ownership in ADR 0003

Tests

• npm run lint -- --diagnostic-level=error
• npm run typecheck
• npm run server:typecheck
• npm test (1064 passed, 4 platform-gated skips)
• npm run test:integration (281 passed, 5 credential-gated skips)
• focused migration/ownership tests (26 passed)
• fresh PostgreSQL migration smoke (62 tables, exact v1 checksum, idempotent rerun)
• npm run guard:big-brain
• npm run guard:llm-tracked
• npm run guard:engine-registry
• npm run build
• Deploy workflow YAML parse and local strategic-patch verification