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/Bench Press/motion.json

@@ -0,0 +1,39 @@
+{
+  "name": "Bench Press",
+  "primary": 1,
+  "working": ["arm_r", "arm_l"],
+  "props": [
+    {"type": "scene", "shapes": [
+      {"kind": "line", "pts": [[58, 124], [162, 124]], "w": 9, "depth": 8},
+      {"kind": "line", "pts": [[78, 129], [78, 150]], "w": 4},
+      {"kind": "line", "pts": [[144, 129], [144, 150]], "w": 4}
+    ]},
+    {"type": "bar", "at": ["hand_r", "hand_l"], "halfLen": 26, "plateR": 12}
+  ],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 0.9,
+      "root": {"pos": [150, 116], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 8, "head": 0,
+      "shoulder_r": 15, "elbow_r": 100,
+      "shoulder_l": 15, "elbow_l": 100,
+      "hip_r": 78, "knee_r": 82, "ankle_r": 5,
+      "hip_l": 78, "knee_l": 82, "ankle_l": 5,
+      "pins": {"foot_r": [196, 148], "foot_l": [200, 150],
+               "hand_r": [93, 100], "hand_l": [97, 102]}
+    },
+    {
+      "hold": 0.4, "tween": 1.2,
+      "root": {"pos": [150, 116], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 8, "head": 0,
+      "shoulder_r": 90, "elbow_r": 5,
+      "shoulder_l": 90, "elbow_l": 5,
+      "hip_r": 78, "knee_r": 82, "ankle_r": 5,
+      "hip_l": 78, "knee_l": 82, "ankle_l": 5,
+      "pins": {"foot_r": [196, 148], "foot_l": [200, 150],
+               "hand_r": [67, 57], "hand_l": [71, 59]}
+    }
+  ]
+}