feat: execute full-repo remaining parity closure plan

tests/NATS.Server.Tests/JetStream/JetStreamClusterGovernanceRuntimeParityTests.cs

@@ -0,0 +1,26 @@
+using NATS.Server.JetStream.Cluster;
+using NATS.Server.JetStream.Models;
+
+namespace NATS.Server.Tests;
+
+public class JetStreamClusterGovernanceRuntimeParityTests
+{
+    [Fact]
+    public async Task Jetstream_cluster_governance_applies_consensus_backed_placement()
+    {
+        var meta = new JetStreamMetaGroup(3);
+        await meta.ProposeCreateStreamAsync(new StreamConfig
+        {
+            Name = "ORDERS",
+            Subjects = ["orders.*"],
+        }, default);
+
+        var planner = new AssetPlacementPlanner(3);
+        var placement = planner.PlanReplicas(2);
+        var replicas = new StreamReplicaGroup("ORDERS", 1);
+        await replicas.ApplyPlacementAsync(placement, default);
+
+        meta.GetState().Streams.ShouldContain("ORDERS");
+        replicas.Nodes.Count.ShouldBe(2);
+    }
+}