Invert Y on the wire, not in the router: the panel keeps tracking the stick

InputRouter.InvertJoystickY flipped the stored axis, so the X/Y dot and
readout moved opposite the physical stick. The toggle now lives on
VRioDevice and negates joystick Y only while building AnalogReply: local
state keeps the physical direction for every source (pad, keys, panel
drags) and only the host sees the flip. Negating a full -8192 deflection
lands one past the 14-bit Max, so the reply clamps it to 8191.

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

src/VRio.App/MainForm.cs

@@ -190,8 +190,8 @@ internal sealed class MainForm : Form
             if (!_kbInput.Checked)
                 _router.ReleaseAllKeys();
         };
-        _invertY.CheckedChanged += (_, _) => _router.InvertJoystickY = _invertY.Checked;
-        _router.InvertJoystickY = _invertY.Checked; // the field initializer raises no event
+        _invertY.CheckedChanged += (_, _) => _device.InvertJoystickY = _invertY.Checked;
+        _device.InvertJoystickY = _invertY.Checked; // the field initializer raises no event
         _kbLights.CheckedChanged += (_, _) =>
         {
             _lampMirror.Enabled = _kbLights.Checked;