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/Bird Dog.info.md

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+# Bird Dog
+
+Anti-rotation drill — extend opposite limbs while the hips and spine refuse to
+twist.
+
+- **Category:** Warm-up and main circuit
+- **Type:** Anti-rotation
+- **Targets:** Spinal erectors, glutes, deep core, shoulder stability
+- **Prescription:** Warm-up 8 per side; main circuit 3 × 8–10 per side, slow
+
+## Setup
+
+On all fours: hands under shoulders, knees under hips, spine neutral, gaze at
+the floor.
+
+## Execution
+
+1. Brace, then reach one arm forward and the *opposite* leg back until both are
+   in line with the torso.
+2. Pause for a beat at full extension — hips stay square to the floor.
+3. Return under control and switch sides.
+
+## Cues
+
+- Imagine a cup of water balanced on the lower back — nothing spills.
+- Reach *long*, not high: heel pushes back, knuckles push forward.
+- Slow, no momentum; the pause is where the work happens.
+
+## Common Mistakes
+
+- Hips rotating open as the leg lifts.
+- Lifting the leg above hip height and arching the lower back.
+- Racing through reps.
+
+## Progression
+
+Single limb only (arm *or* leg) → opposite arm + leg → paused 3-count hold →
+elbow-to-knee touch under the body between reps → hands on an unstable surface