Give the watch workout screen entirely to the up/down timer

The half-and-half split (paged timer over the looping form-guide figure)
is now iPhone-only. On the watch the ExerciseProgressView TabView fills the
whole screen — the figure slot is gone from both the active flow and the
Completed state, and the ExerciseFigure sources and ExerciseMotions
resources are dropped from the watch target since nothing there uses them.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

CHANGELOG.md

@@ -1,5 +1,7 @@
 **July 2026**
 
+On Apple Watch, the workout screen now gives its whole display to the set and rest timer, without the form-guide figure shown on iPhone.
+
 Barbells and pull-up bars in the animated form guide now turn with the figure as the view circles, instead of hovering fixed on screen.
 
 The goblet squat form guide now holds the weight at the chest with elbows tucked down, instead of flaring oddly.