Automatic finally reserves the right space under the keyboard on every
phone and navigation setting the issue-#1 reporter measured.

The rule is now one subtraction, and it is his: the system's furniture
reaches max(tappable, navigation) pixels up from the bottom of the
screen; the framework has already lifted the keyboard window some
distance off that bottom; the band under the keys is the difference.
On a phone whose window sits at the very bottom that is the whole
furniture - what Always gave, and what worked for him. On a phone whose
window is already placed above the bar it is little or nothing, which is
what kept Always from being the default.

Earlier versions measured the lift and then used it as a cap on the
navigation bar alone, which changed nothing on exactly the phones that
were reporting the bug. The settings readout now shows the lift.
