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/Crunch/motion.json

@@ -0,0 +1,29 @@
+{
+  "name": "Crunch",
+  "primary": 2,
+  "working": ["spine"],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 0.8,
+      "root": {"pos": [166, 146], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 12, "head": 0,
+      "shoulder_r": 155, "elbow_r": 140,
+      "shoulder_l": 155, "elbow_l": 140,
+      "hip_r": 75, "knee_r": 85, "ankle_r": 5,
+      "hip_l": 75, "knee_l": 85, "ankle_l": 5,
+      "pins": {"foot_r": [205, 148], "foot_l": [209, 150]}
+    },
+    {
+      "hold": 0.6, "tween": 1.0,
+      "root": {"pos": [166, 144], "pitch": -90},
+      "spine": [14, 34],
+      "neck": 30, "head": 0,
+      "shoulder_r": 150, "elbow_r": 140,
+      "shoulder_l": 150, "elbow_l": 140,
+      "hip_r": 75, "knee_r": 85, "ankle_r": 5,
+      "hip_l": 75, "knee_l": 85, "ankle_l": 5,
+      "pins": {"foot_r": [205, 148], "foot_l": [209, 150]}
+    }
+  ]
+}