Author the machine exercise circuit with props and corrected hip machine motions

Fourteen Planet Fitness machine exercises join the rig library, each with
authored motion, info page, and schematic equipment via the new props layer
(scene shapes, cables, bars, pads) rendered in lockstep by render.py and the
in-app figure renderer. Abductor and Adductor are authored face-on with the
real seated machine motion — knees-bent legs swinging apart/together against
knee pads — replacing the earlier middle-split depiction. The watch target
now bundles the figure renderer and motion rigs too.

Claude-Session: https://claude.ai/code/session_01LEoff8bXGBS83tK1c55Mf7

Workouts/Resources/ExerciseMotions/Abdominal.info.md

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+# Abdominal
+
+The seated crunch machine — loaded spinal flexion with the lower back
+supported.
+
+- **Category:** Main circuit
+- **Type:** Machine-based trunk flexion
+- **Targets:** Rectus abdominis, deep core
+- **Prescription:** 4 × 10
+
+## Setup
+
+Sit with the pads resting against your chest and your feet flat on the
+platform. Grip the handles lightly and set the seat so your hips stay tucked
+into the base of the back pad.
+
+## Execution
+
+1. Contract your abs to curl your ribs down toward your pelvis, driving the
+   chest pad forward.
+2. Pause at the bottom of the crunch, feeling the abs fully shortened.
+3. Return under control until the torso is tall again — don't let the weight
+   yank you back up.
+
+## Cues
+
+- Curl the spine, don't just hinge at the hips — think "shorten the front".
+- Keep your lower back in contact with the pad throughout.
+- Let the abs move the weight; the arms only steady the handles.
+
+## Common Mistakes
+
+- Pulling with the arms or shoulders instead of the abs.
+- Hinging from the hips with a flat, rigid spine.
+- Rushing the return and bouncing out of the top.
+
+## Progression
+
+Add weight once all four sets of ten are a controlled curl; slow the lowering
+phase to three seconds for extra time under tension.