Fix durable V014 migration preview

[azurras]

What changed

• accept the two exact V014 migration-record lifecycle field orders witnessed from fresh conversion and durable completion
• keep every existing V014 identity, checksum, value, BSON type, class, and source-authority check
• add real-Mongo negative coverage for third-order, missing/extra-field, wrong-class/type, and missing-source records

Root cause

The guarded preview accepted only the fresh converter order. Production has the equally valid durable lifecycle order produced when Spring Data inserts _class and later appends completedAt, so preview failed closed before any effect.

Safety

• no production record rewrite or normalization
• no command/result, manifest, ledger, backup, cutover, rollback, or deletion behavior change
• cutover remains blocked until this fix is merged and the protected read-only preview passes

Validation

• disposable Mongo migration harness: 3/3, including 468 interruption boundaries
• Node syntax checks and contracts: 9/9
• cbell-lib: 123/123
• website Java: 1,876 tests, 0 failures/errors, 75 guarded skips
• full :cbell-lib:test :website:check :website:bootJar: green
• production PowerShell suite: 672 passed, 0 failed, 28 guarded skips
• independent task review and final scoped review: zero Critical/Important findings