Add the free-weight canon and bodyweight staples (16 exercises)

Squat/lunge: Barbell Squat, Goblet Squat, Bodyweight Squat, Lunge.
Bench station: Bench Press, Incline Bench Press, Dumbbell Bench Press,
Dumbbell Fly (the fly authors the face-on camera for its frontal arc).
Dumbbell rack: Dumbbell Row, Dumbbell Shoulder Press, Dumbbell Curl,
Lateral Raise - first uses of the dumbbell prop. Bodyweight: Push-Up,
Pull-Up, Crunch, Dip.

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

Exercise Library/Bodyweight Squat/motion.json

@@ -0,0 +1,30 @@
+{
+  "name": "Bodyweight Squat",
+  "primary": 2,
+  "camera": {"zoom": 0.7},
+  "working": ["leg_r", "leg_l"],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 0.9,
+      "root": {"pos": [160, 64], "pitch": 4},
+      "spine": [0, 0],
+      "neck": 2, "head": -6,
+      "shoulder_r": 6, "elbow_r": 5,
+      "shoulder_l": 6, "elbow_l": 5,
+      "hip_r": 4, "knee_r": 3, "ankle_r": 0,
+      "hip_l": 4, "knee_l": 3, "ankle_l": 0,
+      "pins": {"foot_r": [160, 148], "foot_l": [164, 150]}
+    },
+    {
+      "hold": 0.4, "tween": 0.9,
+      "root": {"pos": [146, 106], "pitch": 30},
+      "spine": [0, -4],
+      "neck": 5, "head": -24,
+      "shoulder_r": 118, "elbow_r": 8,
+      "shoulder_l": 118, "elbow_l": 8,
+      "hip_r": 98, "knee_r": 118, "ankle_r": 22,
+      "hip_l": 98, "knee_l": 118, "ankle_l": 22,
+      "pins": {"foot_r": [160, 148], "foot_l": [164, 150]}
+    }
+  ]
+}