feat(audit): EventId + CorrelationId columns + filtered unique index (F3 + F4)

ConfigAuditLog gains two nullable columns (EventId, CorrelationId) + a filtered
unique index UX_ConfigAuditLog_EventId. EF migration
20260526105027_AddConfigAuditLogEventIdColumns is additive (nullable + filtered
index = legacy rows backfill cleanly).

AuditWriterActor now writes EventId + CorrelationId into the dedicated columns
instead of synthesising a JSON wrapper into DetailsJson. Cross-restart dedup
is now real: a retry of an already-flushed batch hits the unique index and
SaveChanges throws; the existing catch drops the duplicate without losing the
rest of the batch.

WrapDetails helper deleted — F4 (its JSON hardening) becomes moot.

AuditWriterActorTests.Details_wrapper_embeds_eventId_and_correlationId renamed
+ rewritten to assert against the columns. All 29 ControlPlane tests pass,
all 95 v2 tests green.

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Migrations/OtOpcUaConfigDbContextModelSnapshot.cs

@@ -165,9 +165,15 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
                         .HasMaxLength(64)
                         .HasColumnType("nvarchar(64)");
 
+                    b.Property<Guid?>("CorrelationId")
+                        .HasColumnType("uniqueidentifier");
+
                     b.Property<string>("DetailsJson")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<Guid?>("EventId")
+                        .HasColumnType("uniqueidentifier");
+
                     b.Property<string>("EventType")
                         .IsRequired()
                         .HasMaxLength(64)
@@ -192,6 +198,11 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Migrations
 
                     b.HasKey("AuditId");
 
+                    b.HasIndex("EventId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ConfigAuditLog_EventId")
+                        .HasFilter("[EventId] IS NOT NULL");
+
                     b.HasIndex("GenerationId")
                         .HasDatabaseName("IX_ConfigAuditLog_Generation")
                         .HasFilter("[GenerationId] IS NOT NULL");