refactor(input): own pointer and callback lifetime

Move camera pointer, framebuffer resize, and retained/devtools input edges behind focused reversible owners. Preserve input priority while making shutdown deactivate callbacks before live-session retirement and retry physical detach without stranding transport teardown.

tests/AcDream.App.Tests/Input/DispatcherMovementInputSourceTests.cs

@@ -112,12 +112,34 @@ public sealed class DispatcherMovementInputSourceTests
         Assert.Throws<InvalidOperationException>(() => source.Bind(second));
     }
 
+    [Fact]
+    public void UnbindRequiresExactDispatcherAndRestoresNeutralCapture()
+    {
+        var source = new DispatcherMovementInputSource();
+        var (first, _, _) = CreateDispatcher();
+        var (other, _, _) = CreateDispatcher();
+        source.Bind(first);
+        first.TrySetAutomationActionHeld(InputAction.MovementForward, held: true);
+
+        source.Unbind(other);
+        Assert.True(source.Capture().Forward);
+        source.Unbind(first);
+
+        Assert.False(source.IsAvailable);
+        Assert.Equal(default, source.Capture());
+    }
+
     private static (InputDispatcher Dispatcher, FakeKeyboard Keyboard, FakeMouse Mouse)
         CreateDispatcher()
     {
         var keyboard = new FakeKeyboard();
         var mouse = new FakeMouse();
-        return (new InputDispatcher(keyboard, mouse, new KeyBindings()), keyboard, mouse);
+        var dispatcher = InputDispatcher.CreateDetached(
+            keyboard,
+            mouse,
+            new KeyBindings());
+        dispatcher.Attach();
+        return (dispatcher, keyboard, mouse);
     }
 
     private sealed class FakeKeyboard : IKeyboardSource