feat(db): V010 audit infrastructure + temporal tables

Applied to SIGCM2 (dev) and SIGCM2_Test.

V010__audit_infrastructure.sql (idempotent, ~280 LoC):
- Filegroups AUDIT_HOT + AUDIT_COLD with physical files (per-DB logical names
  via DB_NAME() prefix to avoid collision in dev/test).
- pf/ps_AuditEvent_Monthly + pf/ps_SecurityEvent_Monthly (RANGE RIGHT,
  DATETIME2(3), 14 boundaries 2026-01..2027-02 → 15 partitions). Job extends
  forward monthly in B11.
- dbo.AuditEvent (partitioned, clustered PK on OccurredAt+Id) + 4 indexes
  (Actor/Target/Action/Correlation) with PAGE compression.
- dbo.SecurityEvent (partitioned) + 3 indexes (Actor/Action_Result/Ip_Failure).
- CHECK constraints: Action LIKE '%.%', ISJSON(Metadata), Result IN (success|failure).
- SYSTEM_VERSIONING ON in Usuario/Rol/Permiso/RolPermiso with 10 YEARS retention +
  PAGE compression in history tables.
- No hard FK on ActorUserId → Usuario.Id (soft FK — audit must survive user deletion).

V010_ROLLBACK.sql: emergency reversal (WARNING: destroys all audit history).

database/README.md: migration order + V010 prod-apply notes.

tests/SIGCM2.TestSupport/SqlTestFixture.cs:
- EnsureV010SchemaAsync() validates audit infra is applied (fails fast with
  clear message if not — migration itself requires ALTER DATABASE privileges
  and is applied manually via sqlcmd).
- Respawn TablesToIgnore extended with *_History (engine rejects direct DELETE
  on system-versioned history tables).

tests/SIGCM2.Api.Tests/Audit/V010MigrationTests.cs — 5 smoke tests:
- AuditEvent insert+roundtrip with CorrelationId.
- CK_AuditEvent_Action rejects Action without '.'.
- CK_AuditEvent_Metadata rejects non-JSON.
- CK_SecurityEvent_Result rejects invalid Result.
- Usuario SYSTEM_VERSIONING: temporal query FOR SYSTEM_TIME AS OF returns
  pre-update state + Usuario_History populated.

Suite: 130/130 passing (previous 124 + spike B0 + 5 new B1). No regressions.

Refs: sdd/udt-010-auditoria-trazabilidad/{spec#REQ-AUD-1,2, #REQ-SEC-1,
design#D-4, tasks}

tests/SIGCM2.TestSupport/SqlTestFixture.cs

@@ -32,16 +32,25 @@ public sealed class SqlTestFixture : IAsyncLifetime
         // V009: update PermisosJson DEFAULT constraint and migrate legacy rows
         await EnsureV009SchemaAsync();
 
+        // V010 (UDT-010): verify audit infrastructure + temporal tables are active.
+        // Applied manually via: sqlcmd ... -i database/migrations/V010__audit_infrastructure.sql
+        await EnsureV010SchemaAsync();
+
         _respawner = await Respawner.CreateAsync(_connection, new RespawnerOptions
         {
             DbAdapter = DbAdapter.SqlServer,
             // Rol is a lookup table seeded by migration V003 — never wipe or Usuario FK breaks.
             // Permiso and RolPermiso are seeded by V005/V006 — never wipe or integration tests lose the permission catalog.
+            // *_History tables: UDT-010 system-versioned — Respawn cannot DELETE them directly (engine rejects).
             TablesToIgnore =
             [
                 new Respawn.Graph.Table("dbo", "Rol"),
                 new Respawn.Graph.Table("dbo", "Permiso"),
                 new Respawn.Graph.Table("dbo", "RolPermiso"),
+                new Respawn.Graph.Table("dbo", "Usuario_History"),
+                new Respawn.Graph.Table("dbo", "Rol_History"),
+                new Respawn.Graph.Table("dbo", "Permiso_History"),
+                new Respawn.Graph.Table("dbo", "RolPermiso_History"),
             ]
         });
 
@@ -232,6 +241,29 @@ public sealed class SqlTestFixture : IAsyncLifetime
         await _connection.ExecuteAsync(sql);
     }
 
+    /// <summary>
+    /// UDT-010 (V010): verifies that the audit infrastructure is present.
+    /// Does NOT re-apply the migration (the ALTER DATABASE ADD FILEGROUP/FILE + partition
+    /// function/scheme creation requires the full script). If missing, fails with a clear
+    /// message pointing to the migration script.
+    /// </summary>
+    private async Task EnsureV010SchemaAsync()
+    {
+        const string check = """
+            SELECT
+                CAST(CASE WHEN OBJECT_ID('dbo.AuditEvent','U')   IS NULL THEN 0 ELSE 1 END AS BIT) AS HasAuditEvent,
+                CAST(CASE WHEN OBJECT_ID('dbo.SecurityEvent','U') IS NULL THEN 0 ELSE 1 END AS BIT) AS HasSecurityEvent,
+                CAST(CASE WHEN EXISTS (SELECT 1 FROM sys.tables WHERE object_id = OBJECT_ID('dbo.Usuario') AND temporal_type = 2) THEN 1 ELSE 0 END AS BIT) AS UsuarioVersioned
+            """;
+        var result = await _connection.QuerySingleAsync<(bool HasAuditEvent, bool HasSecurityEvent, bool UsuarioVersioned)>(check);
+        if (!result.HasAuditEvent || !result.HasSecurityEvent || !result.UsuarioVersioned)
+        {
+            throw new InvalidOperationException(
+                "V010 audit infrastructure is not applied in the test database. " +
+                "Run: sqlcmd -S <server> -d SIGCM2_Test -U <user> -P <pass> -i database/migrations/V010__audit_infrastructure.sql");
+        }
+    }
+
     /// <summary>
     /// Applies V009 schema changes idempotently to the test database.
     /// Mirrors V009__activate_permisos_overrides.sql.