fix(input): free-fly is unreachable, and Escape no longer answers to it

User report: "ESC is hardwired to Freefly which it should not be ... the
freefly should really be discarded. Should not be in the client."

Two separate things were true.

Escape ran a priority chain — cancel target mode, else EXIT FLY MODE, else
leave player mode, else close a window — so in a session that had reached the
free-fly camera, Escape spent itself on that rung instead of doing what the
player expected. The rung is gone; a session somehow in fly mode now falls
through to the next one.

And free-fly was still bound: Ctrl+Shift+F in RetailDefaults (the table
production actually loads) and plain F in AcdreamCurrentDefaults (dead since
K.1c, removed anyway so it cannot be revived by accident). The comment on the
live binding advertised two other ways in — the ImGui View menu and the Debug
panel's "Toggle Free-Fly Mode" button — but BOTH went away with
AcDream.UI.ImGui at Campaign V, so the shortcut was the last route in. It is
now unbound, and a test pins that across both default tables.

This makes free-fly unreachable rather than deleted. The implementation still
spans 25 files (CameraController, FlyCamera, the dispatcher capture, pointer
controller, composition, and a streaming observer source), and ripping that out
at the end of a long session is how a regression lands in the camera. Scoped as
its own follow-up; unbinding is what fixes the reported behaviour today.

The Escape priority test was updated rather than deleted: its middle row now
asserts the fall-through, so the removed rung is documented by a passing test
instead of by its absence.

Solution builds clean; full hermetic gate green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/AcDream.UI.Abstractions.Tests/Input/KeyBindingsRetailTests.cs

@@ -243,4 +243,28 @@ public class KeyBindingsRetailTests
         Assert.NotNull(bound);
         Assert.Equal(InputAction.ToggleOptionsPanel, bound!.Value.Action);
     }
+
+    /// <summary>
+    /// The developer free-fly camera must not be reachable from the keyboard.
+    /// </summary>
+    /// <remarks>
+    /// It is a camera retail never had, and a player who lands in it finds the
+    /// client in a state nothing in the retail UI explains. Its two other ways
+    /// in — the ImGui View menu and the Debug panel button — went away with
+    /// AcDream.UI.ImGui at Campaign V, so a binding was the last route.
+    /// </remarks>
+    [Fact]
+    public void NoDefaultBindingReachesTheFreeFlyCamera()
+    {
+        foreach (KeyBindings bindings in new[]
+                 {
+                     KeyBindings.RetailDefaults(),
+                     KeyBindings.AcdreamCurrentDefaults(),
+                 })
+        {
+            Assert.DoesNotContain(
+                bindings.All,
+                binding => binding.Action == InputAction.AcdreamToggleFlyMode);
+        }
+    }
 }