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/Goblet Squat/motion.json

@@ -0,0 +1,35 @@
+{
+  "name": "Goblet Squat",
+  "primary": 2,
+  "camera": {"zoom": 0.72},
+  "working": ["leg_r", "leg_l"],
+  "props": [
+    {"type": "dumbbell", "at": ["hand_r", "hand_l"], "angle": 90, "halfLen": 8, "plateR": 5}
+  ],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 1.0,
+      "root": {"pos": [160, 66], "pitch": 5},
+      "spine": [0, 0],
+      "neck": 2, "head": -6,
+      "shoulder_r": 38, "elbow_r": 125,
+      "shoulder_l": 38, "elbow_l": 125,
+      "hip_r": 5, "knee_r": 4, "ankle_r": 0,
+      "hip_l": 5, "knee_l": 4, "ankle_l": 0,
+      "pins": {"foot_r": [162, 148], "foot_l": [166, 150],
+               "hand_r": [176, -2], "hand_l": [180, 0]}
+    },
+    {
+      "hold": 0.4, "tween": 1.0,
+      "root": {"pos": [150, 104], "pitch": 22},
+      "spine": [0, -4],
+      "neck": 4, "head": -18,
+      "shoulder_r": 46, "elbow_r": 120,
+      "shoulder_l": 46, "elbow_l": 120,
+      "hip_r": 96, "knee_r": 116, "ankle_r": 20,
+      "hip_l": 96, "knee_l": 116, "ankle_l": 20,
+      "pins": {"foot_r": [162, 148], "foot_l": [166, 150],
+               "hand_r": [190, 40], "hand_l": [194, 42]}
+    }
+  ]
+}