fix(site-runtime): site-side compile failure now rejects the deployment per spec (S3) — synchronous validation gate before actor creation

Validation runs on the actor thread (not off-thread as the plan sketched): piping
the verdict back to self reorders concurrent deploys relative to each other and to
delete/disable, breaking the redeploy-supersede FIFO ordering (SR020/SR029). A deploy
is an infrequent admin command, so a brief synchronous Roslyn compile is acceptable.

tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Actors/DeploymentManagerActorTests.cs

@@ -232,6 +232,40 @@ public class DeploymentManagerActorTests : TestKit, IDisposable
         Assert.Equal("NewPump", response.InstanceUniqueName);
     }
 
+    // ── S3: site-side compile failure rejects the deployment (no partial state) ──
+
+    private static string MakeConfigWithBrokenScriptJson(string instanceName) =>
+        JsonSerializer.Serialize(new FlattenedConfiguration
+        {
+            InstanceUniqueName = instanceName,
+            Attributes = [new ResolvedAttribute { CanonicalName = "TestAttr", Value = "42", DataType = "Int32" }],
+            Scripts = [new ResolvedScript { CanonicalName = "S1", Code = "this is not C# ~~~" }]
+        });
+
+    [Fact]
+    public async Task Deploy_WithNonCompilingScript_ReportsFailed_AndCreatesNoInstanceActor()
+    {
+        var actor = CreateDeploymentManager();
+        await Task.Delay(500); // wait for empty startup
+
+        actor.Tell(new DeployInstanceCommand(
+            "dep-bad", "bad-instance", "r1",
+            MakeConfigWithBrokenScriptJson("bad-instance"), "admin", DateTimeOffset.UtcNow));
+
+        var resp = ExpectMsg<DeploymentStatusResponse>(TimeSpan.FromSeconds(10));
+        Assert.Equal(DeploymentStatus.Failed, resp.Status);
+        Assert.NotNull(resp.ErrorMessage);
+        Assert.Contains("compil", resp.ErrorMessage!, StringComparison.OrdinalIgnoreCase);
+
+        // No partial state applied: instance actor must not exist …
+        Sys.ActorSelection(actor.Path / "bad-instance").Tell(new Identify(1));
+        Assert.Null(ExpectMsg<ActorIdentity>().Subject);
+
+        // … and no config must have been persisted.
+        var configs = await _storage.GetAllDeployedConfigsAsync();
+        Assert.DoesNotContain(configs, c => c.InstanceUniqueName == "bad-instance");
+    }
+
     // ── M1.6: site event log `deployment` category ─────────────────────────
 
     [Fact]