Default bindings: pad-mandatory axes, full keyboard button field

Rework the shipped default profile around a required Xbox controller,
refined from live-game testing:

- All five axes are pad-only now (left stick / triggers / right stick);
  the key-axis bindings (arrows/WASD-style deflect and rate) are gone
  from the defaults, though the grammar remains supported.
- Keyboard becomes the button field, geometry mirroring the panel:
  number row + QWERTY row = upper MFD bank, home + bottom rows =
  lower MFD bank as two 4-key blocks with an unbound gap key (G / B)
  standing in for the panel keypad gap, F1-F6 / F7-F12 = the
  Secondary / Screen columns top-to-bottom (0x16/0x17, 0x1E/0x1F
  deliberately unmapped), numpad = the full internal keypad with the
  hex keys on the operators (/ * - + . Enter = A-F).
- Hat rides the arrow keys, Main stays on Space; Pinky / Middle /
  Upper / Panic are pad-only so no panic key sits inside the MFD field.
- Pad B and LeftShoulder swap to Middle / Panic.
- Rest of the throttle column and the external keypad stay unmapped.

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

tests/VRio.Core.Tests/InputRouterTests.cs

@@ -13,8 +13,8 @@ public class BindingProfileFormatTests
         BindingProfile profile = BindingProfileFormat.Parse(BindingProfileFormat.DefaultText, out var errors);
 
         Assert.Empty(errors);
-        Assert.True(profile.KeyButtons.Count >= 19);   // named buttons + numpad digits
-        Assert.Equal(8, profile.KeyAxes.Count);        // arrows + W/S + Q/E
+        Assert.Equal(73, profile.KeyButtons.Count);    // 40 MFD + 12 columns + 16 keypad + Space + 4 hat
+        Assert.Empty(profile.KeyAxes);                 // axes are pad-only in the default profile
         Assert.Equal(10, profile.PadButtons.Count);
         Assert.Equal(5, profile.PadAxes.Count);
     }