v0.13.0 Priority 0 — Complete T04 State Engine V2

Product Owner decision: v0.12.0 omits T04, ships with the existing stable snapshot state authority, and gives T04 top priority in v0.13.0. Source: Issue #82. This issue is the v0.13 top-priority release milestone.

In-scope for v0.13.0

• State Engine V2 canonical append-only event ledger, index and derived snapshot, migration and idempotent recovery, crash consistency and source-bound evidence.
• Full Windows legacy-backup restore/recovery support remains required, not downgraded or disabled. Resolve the original Windows crash-durability Issue T04 P1: Windows restore-journal deletion must follow durable directory rename #73 (journal durable publication, original displacement, stage promotion, clean acknowledgement, crash recovery and controlled power-loss evidence).
• Preserve the v0.12 existing-stable-state compatibility adapter and all public /dk commands during migration.
• Independent three-role code, architecture and security review on exact source, issue thread closure, real Windows and Ubuntu CI, deterministic risk-3 acceptance.
• Outstanding T04 criteria AC-012, AC-013, AC-014, AC-015 and AC-034 (v0.12 release-scope amendment expressly records these as DEFERRED, not PASS).
• T04 PR fix(v0.12 T04): crash-safe event append, process locks and restore confinement #70 remains a development candidate and must not be merged into v0.12.0.

Delivery order

1. Rebase T04 development on released v0.12.0 source after publication.
2. Confirm exact supported Windows filesystem/OS durability contract using authoritative evidence and a controlled crash/recovery test environment.
3. Fix outstanding source defects and run adversarial power-loss/rollback tests.
4. Obtain authenticated independent role reviews and deterministic T04 ACCEPTED verdict.
5. Ship only through the version's protected release workflow.

Priority: Blocker / P0 for v0.13.0. Do not close Issue #73 or mark T04 accepted before verified crash-durability evidence.