Give cross-body bars a true 3D axis and fix the goblet squat hold

The orbit was always a real camera orbit — figure and props share one
rigid rotation — but a bar's screen-space angle authored the wrong 3D
rod: the default horizontal encoded a rod along the body axis, so
barbells hovered fixed on screen and vanished at the head-on view
where they should span widest. Line props now take "axis": "z" (both
renderers in lockstep, fixture-pinned): the world left-right direction
projects through the camera pitch like the floor quad — end-on plates
in profile, full span face-on, swinging with the hands in between.
Applied to the ten cross-body bars; vertical handles were already
orbit-invariant.

Goblet Squat's hand pins sat so close to the shoulders that the
two-bone IK was degenerate, flipping between a chicken-wing and an
elbow-behind solve; re-pinned level with the shoulders so the elbows
tuck straight down through the whole rep.

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

CHANGELOG.md

@@ -1,5 +1,13 @@
 **July 2026**
 
+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.
+
+Each set you complete is now recorded — adjust the reps or weight you actually did right from the rest screen.
+
+The Weight Progression chart and workout volume now reflect what you actually lifted, not just the plan.
+
 A Live Activity now shows your current exercise, set, and rest countdown on the Lock Screen and in the Dynamic Island.
 
 Any exercise from the library can now be added mid-workout, planned from your last time doing it.