refactor(app): compose content effects and audio startup

Move Phase-2 startup behind typed composition/publication boundaries, replace the GameWindow-capturing PhysicsScript gate with a focused deferred source, and own animation-hook registrations reversibly. Make OpenAL construction and teardown transactional so every device, context, source, and buffer prefix is retryable without replay.

tests/AcDream.App.Tests/Rendering/Vfx/EntityEffectAdvanceSourceTests.cs

@@ -0,0 +1,43 @@
+using AcDream.App.Rendering.Vfx;
+
+namespace AcDream.App.Tests.Rendering.Vfx;
+
+public sealed class EntityEffectAdvanceSourceTests
+{
+    [Fact]
+    public void DefaultsOpenThenForwardsOneExactOwnerAndUnbindsOnlyThatOwner()
+    {
+        var source = new DeferredEntityEffectAdvanceSource();
+        var first = new Target(false);
+        var other = new Target(true);
+
+        Assert.True(source.CanAdvanceOwner(42));
+        source.Bind(first);
+        Assert.False(source.CanAdvanceOwner(42));
+        source.Unbind(other);
+        Assert.False(source.CanAdvanceOwner(42));
+        source.Unbind(first);
+        Assert.True(source.CanAdvanceOwner(42));
+        source.Bind(other);
+        Assert.True(source.CanAdvanceOwner(42));
+    }
+
+    [Fact]
+    public void RejectsASecondOwnerAndDeactivationIsTerminalAndOpenForShutdown()
+    {
+        var source = new DeferredEntityEffectAdvanceSource();
+        var first = new Target(false);
+        source.Bind(first);
+
+        Assert.Throws<InvalidOperationException>(() => source.Bind(new Target(true)));
+        source.Deactivate();
+
+        Assert.True(source.CanAdvanceOwner(1));
+        Assert.Throws<ObjectDisposedException>(() => source.Bind(first));
+    }
+
+    private sealed class Target(bool result) : IEntityEffectAdvanceSource
+    {
+        public bool CanAdvanceOwner(uint ownerLocalId) => result;
+    }
+}