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/Pull-Up/motion.json

@@ -0,0 +1,33 @@
+{
+  "name": "Pull-Up",
+  "primary": 2,
+  "camera": {"zoom": 0.7},
+  "working": ["arm_r", "arm_l"],
+  "props": [
+    {"type": "bar", "at": ["hand_r", "hand_l"], "halfLen": 24}
+  ],
+  "frames": [
+    {
+      "hold": 0.5, "tween": 1.0,
+      "root": {"pos": [156, 99]},
+      "spine": [0, 0],
+      "neck": 2, "head": -6,
+      "shoulder_r": 182, "elbow_r": 5,
+      "shoulder_l": 182, "elbow_l": 5,
+      "hip_r": 35, "knee_r": 120, "ankle_r": -30,
+      "hip_l": 35, "knee_l": 120, "ankle_l": -30,
+      "pins": {"hand_r": [154, -46], "hand_l": [158, -44]}
+    },
+    {
+      "hold": 0.4, "tween": 1.3,
+      "root": {"pos": [156, 67]},
+      "spine": [0, 0],
+      "neck": 4, "head": -10,
+      "shoulder_r": 150, "elbow_r": 125,
+      "shoulder_l": 150, "elbow_l": 125,
+      "hip_r": 35, "knee_r": 120, "ankle_r": -30,
+      "hip_l": 35, "knee_l": 120, "ankle_l": -30,
+      "pins": {"hand_r": [154, -46], "hand_l": [158, -44]}
+    }
+  ]
+}