feat: wire SQLite replication between site nodes and fix ConfigurationDatabase tests

Add SiteReplicationActor (runs on every site node) to replicate deployed
configs and store-and-forward buffer operations to the standby peer via
cluster member discovery and fire-and-forget Tell. Wire ReplicationService
handler and pass replication actor to DeploymentManagerActor singleton.

Fix 5 pre-existing ConfigurationDatabase test failures: RowVersion NOT NULL
on SQLite, stale migration name assertion, and seed data count mismatch.

tests/ScadaLink.ConfigurationDatabase.Tests/ConcurrencyTests.cs

@@ -22,12 +22,15 @@ public class ConcurrencyTestDbContext : ScadaLinkDbContext
     {
         base.OnModelCreating(modelBuilder);
 
-        // Replace the SQL Server RowVersion with an explicit concurrency token for SQLite
-        // Remove the shadow RowVersion property and add a visible ConcurrencyStamp
+        // Replace the SQL Server RowVersion with an explicit concurrency token for SQLite.
+        // SQLite can't auto-generate rowversion, so disable it and use Status as the token instead.
         modelBuilder.Entity<DeploymentRecord>(builder =>
         {
-            // The shadow RowVersion property from the base config doesn't work in SQLite.
-            // Instead, use Status as a concurrency token for the test.
+            builder.Property(d => d.RowVersion)
+                .IsRequired(false)
+                .IsConcurrencyToken(false)
+                .ValueGeneratedNever();
+
             builder.Property(d => d.Status).IsConcurrencyToken();
         });
     }

tests/ScadaLink.ConfigurationDatabase.Tests/RepositoryTests.cs

@@ -68,8 +68,9 @@ public class SecurityRepositoryTests : IDisposable
         await _repository.SaveChangesAsync();
 
         var designMappings = await _repository.GetMappingsByRoleAsync("Design");
-        Assert.Single(designMappings);
-        Assert.Equal("Designers", designMappings[0].LdapGroupName);
+        // Seed data includes "SCADA-Designers" with role "Design", plus the one we added
+        Assert.Equal(2, designMappings.Count);
+        Assert.Contains(designMappings, m => m.LdapGroupName == "Designers");
     }
 
     [Fact]

tests/ScadaLink.ConfigurationDatabase.Tests/SqliteTestHelper.cs

@@ -1,13 +1,15 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using ScadaLink.Commons.Entities.Deployment;
 using ScadaLink.ConfigurationDatabase;
 
 namespace ScadaLink.ConfigurationDatabase.Tests;
 
 /// <summary>
-/// Test DbContext that maps DateTimeOffset to a sortable string format for SQLite.
-/// EF Core 10 SQLite provider does not support ORDER BY on DateTimeOffset columns.
+/// Test DbContext that adapts SQL Server-specific features for SQLite:
+/// - Maps DateTimeOffset to sortable ISO 8601 strings (SQLite has no native DateTimeOffset ORDER BY)
+/// - Replaces SQL Server RowVersion with a nullable byte[] column (SQLite can't auto-generate rowversion)
 /// </summary>
 public class SqliteTestDbContext : ScadaLinkDbContext
 {
@@ -19,6 +21,16 @@ public class SqliteTestDbContext : ScadaLinkDbContext
     {
         base.OnModelCreating(modelBuilder);
 
+        // SQLite cannot auto-generate SQL Server rowversion values.
+        // Replace with a nullable byte[] column so inserts don't fail with NOT NULL constraint.
+        modelBuilder.Entity<DeploymentRecord>(builder =>
+        {
+            builder.Property(d => d.RowVersion)
+                .IsRequired(false)
+                .IsConcurrencyToken(false)
+                .ValueGeneratedNever();
+        });
+
         // Convert DateTimeOffset to ISO 8601 string for SQLite so ORDER BY works
         var converter = new ValueConverter<DateTimeOffset, string>(
             v => v.UtcDateTime.ToString("o"),

tests/ScadaLink.ConfigurationDatabase.Tests/UnitTest1.cs

@@ -21,13 +21,7 @@ public class DbContextTests : IDisposable
 
     public DbContextTests()
     {
-        var options = new DbContextOptionsBuilder<ScadaLinkDbContext>()
-            .UseSqlite("DataSource=:memory:")
-            .Options;
-
-        _context = new ScadaLinkDbContext(options);
-        _context.Database.OpenConnection();
-        _context.Database.EnsureCreated();
+        _context = SqliteTestHelper.CreateInMemoryContext();
     }
 
     public void Dispose()
@@ -429,6 +423,6 @@ public class MigrationHelperTests : IDisposable
     {
         // Verify the InitialCreate migration is detected as pending
         var pending = _context.Database.GetPendingMigrations().ToList();
-        Assert.Contains(pending, m => m.Contains("InitialCreate"));
+        Assert.Contains(pending, m => m.Contains("InitialSchema"));
     }
 }