Adds 4 tests in EnsureDatabaseSeedAuditTests:
- EnsureDatabaseAsync_WithSeedAuditOwnerCreated_DoesNotResetOwnerPasswordHash
- EnsureDatabaseAsync_NewDbContextAfterPasswordChange_PreservesChangedPassword
- EnsureDatabaseAsync_WithSeedAuditButNoUsers_DoesNotReSeedOwner
- EnsureDatabaseAsync_WithoutSeedAudit_WouldCreateOwner
Verifies that once SeedAudit contains owner_created, subsequent
EnsureDatabaseAsync calls (simulating pod restarts) do NOT reset
the owner's password hash. Covers the owner_created SeedAudit guard.
