refactor(runtime): move session lifetime and ordered transport

Move the canonical WorldSession generation, connect/enter/tick/stop transaction, inbound subscription owner, and retryable teardown acknowledgements into AcDream.Runtime. Keep App as a borrowing graphical host with a single inertable command projection and no mirrored session state.

Validated by 79 Runtime tests, 3,776 App tests with three existing skips, the Release solution build, and 8,428 complete Release tests with five existing skips.

Co-authored-by: Codex <codex@openai.com>

tests/AcDream.App.Tests/Net/GameWindowLiveSessionOwnershipTests.cs

@@ -2,6 +2,8 @@ using System.Reflection;
 using AcDream.App.Rendering;
 using AcDream.App.Net;
 using AcDream.Core.Net;
+using AcDream.Runtime;
+using AcDream.Runtime.Session;
 
 namespace AcDream.App.Tests.Net;
 
@@ -30,6 +32,28 @@ public sealed class GameWindowLiveSessionOwnershipTests
         Assert.DoesNotContain(fields, field => field.Name == "_liveSessionCommands");
     }
 
+    [Fact]
+    public void GraphicalSessionSourceBorrowsCanonicalRuntimeState()
+    {
+        FieldInfo[] fields = typeof(LiveSessionAppSource).GetFields(PrivateInstance);
+
+        Assert.Equal(2, fields.Length);
+        Assert.Contains(
+            fields,
+            field => field.Name == "_session"
+                && field.FieldType == typeof(LiveSessionController));
+        Assert.Contains(
+            fields,
+            field => field.Name == "_commands"
+                && field.FieldType == typeof(LiveSessionCommandSurface));
+        Assert.DoesNotContain(fields, field => field.FieldType == typeof(WorldSession));
+        Assert.DoesNotContain(fields, field => field.FieldType == typeof(bool));
+        Assert.DoesNotContain(
+            fields,
+            field => field.FieldType == typeof(RuntimeGenerationToken)
+                || field.FieldType == typeof(ulong));
+    }
+
     [Theory]
     [InlineData("TryStartLiveSession")]
     [InlineData("ClearInboundEntityState")]