C2/C3: restore rotation keybinds (REPLY/LS-cycle) + focus contract routing on the focused chat surface

HellionChat/Ui/Windows/MainWindow.cs

@@ -16,7 +16,7 @@ namespace HellionChat.Ui.Windows;
 // Components are fully qualified through the Ui.Components prefix so the
 // old Ui.StatusBar type (still alive until the cleanup block removes it)
 // cannot shadow the new layer through parent-namespace resolution.
-internal sealed class MainWindow : Window
+internal sealed class MainWindow : Window, IFocusableChatWindow
 {
     private const float DefaultWidth = 620f;
     private const float DefaultHeight = 340f;
@@ -205,6 +205,18 @@ internal sealed class MainWindow : Window
         _input.Activate = true;
     }
 
+    // IFocusableChatWindow — the keybind tail resolves which surface owns the
+    // input focus before routing a channel-set/REPLY/prefill at it (C3).
+    public bool HasFocusedInput => _input.IsFocused;
+
+    // Arm-and-hold: field writes only, safe from the framework thread; the draw
+    // path applies the actual ImGui focus next frame (same path as ActivateChat).
+    public void RequestInputFocus()
+    {
+        BringToFront();
+        _input.Activate = true;
+    }
+
     // new-shadow on Window.Toggle so the open path also writes Config. A user-hide
     // counts as "not visible", so /hellion is a reliable one-press recovery even when
     // the Enter keybind can't fire (DirectChat / a focused game text field).