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/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]