refactor(app): compose session and player startup

Move streaming, live-session, hydration, local-player, combat, and teleport construction behind the typed Phase-7 boundary. Add exact-owner runtime bindings and focused spawn-claim classification so partial startup rolls back without retaining old session targets while preserving the accepted construction and frame dependencies.

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

tests/AcDream.App.Tests/World/LiveEntityHydrationControllerTests.cs

@@ -32,6 +32,24 @@ public sealed class LiveEntityHydrationControllerTests
         Assert.Throws<InvalidOperationException>(() => bridge.Bind(_ => false));
     }
 
+    [Fact]
+    public void ParentAcceptanceOwnedBindingReleasesExactlyAndAllowsRebind()
+    {
+        var bridge = new DeferredLiveEntityParentAcceptance();
+        Func<ParentEvent.Parsed, bool> first = _ => true;
+        Func<ParentEvent.Parsed, bool> second = _ => false;
+
+        IDisposable firstBinding = bridge.BindOwned(first);
+        Assert.True(bridge.TryAccept(default));
+        Assert.Throws<InvalidOperationException>(() => bridge.BindOwned(second));
+
+        firstBinding.Dispose();
+        using IDisposable secondBinding = bridge.BindOwned(second);
+        firstBinding.Dispose();
+
+        Assert.False(bridge.TryAccept(default));
+    }
+
     [Fact]
     public void FreshCreate_PublishesCanonicalOrderAndReadyAfterMaterialization()
     {
@@ -1580,6 +1598,25 @@ public sealed class LiveEntityHydrationControllerTests
             deferred.Bind(new RecordingNetworkSink()));
     }
 
+    [Fact]
+    public void DeferredNetworkOwnedBindingReleasesExactlyAndAllowsRebind()
+    {
+        var deferred = new DeferredLiveEntityNetworkUpdateSink();
+        var first = new RecordingNetworkSink();
+        var second = new RecordingNetworkSink();
+
+        IDisposable firstBinding = deferred.BindOwned(first);
+        Assert.Throws<InvalidOperationException>(() => deferred.BindOwned(second));
+
+        firstBinding.Dispose();
+        using IDisposable secondBinding = deferred.BindOwned(second);
+        firstBinding.Dispose();
+        deferred.ApplySameGeneration(default);
+
+        Assert.Equal(0, first.ApplyCount);
+        Assert.Equal(1, second.ApplyCount);
+    }
+
     private const uint Guid = 0x70000001u;
     private const uint Cell = 0x01010001u;