Hand a put-down controller's side to the cameras

- Started with the controllers connected, a race stayed on them: Horizon OS switches all input
  between controllers and hands, and back to the controllers as soon as one lying on a table moves
  (a Quest 3 log went touch_controller, simple_controller, touch_controller within seconds). An
  app cannot disconnect the controllers.
- With tracked hands on, the input now resumes XR_META_simultaneous_hands_and_controllers (Meta's
  multimodal), which overrides that switching: a controller not in a hand no longer owns it, so the
  cameras track that hand at once, and a held controller keeps working. Paused again when the
  option goes off; a refused resume is logged and not retried until the option is toggled.
- A hand is bare when its squeeze action is inactive and it either drives khr/simple_controller or
  has camera-tracked joints, since a free hand under simultaneous tracking may get a profile our
  actions are not bound in. Docs: OPENXR.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

android/app/src/main/res/values/strings.xml

@@ -534,7 +534,7 @@
     <string name="vr_hand_steering">Hand steering</string>
     <string name="vr_hand_steering_helper">In the cockpit, squeeze a grip near the steering wheel or handlebar to grab it, and turn it to steer. Releasing both grips gives steering back to the stick. Hand steering by heurazy.</string>
     <string name="vr_hand_tracking">Tracked hands</string>
-    <string name="vr_hand_tracking_helper">The cockpit hands follow your own. Holding the controllers, the fingers follow their touch sensors. Put the controllers down to drive with bare hands: close a hand on the wheel to hold it, which also holds the gas; pinch with a free hand to use an item; flick your hands up for a trick; pinch with your left palm facing you to pause. In menus, a right pinch is A. Choose Automatic drift. Needs hand tracking on in the headset\'s settings.</string>
+    <string name="vr_hand_tracking_helper">The cockpit hands follow your own. Holding the controllers, the fingers follow their touch sensors; put one down and the cameras track that hand at once. Put the controllers down to drive with bare hands: close a hand on the wheel to hold it, which also holds the gas; pinch with a free hand to use an item; flick your hands up for a trick; pinch with your left palm facing you to pause. In menus, a right pinch is A. Choose Automatic drift. Needs hand tracking on in the headset\'s settings.</string>
     <string name="vr_lean_back">Lean back angle</string>
     <string name="vr_lean_back_helper">Tilts the race view back for playing reclined. 0 applies no tilt.</string>