Ship the 47-exercise library in-app: export, fixtures, tests, docs

render.py --export bundles the 25 new motion rigs and info pages;
figure-fixtures.json regenerated for all 47 (the Swift solver reproduces
every new motion, including negative-y pins and the new prop uses). The
fixture count assertion moves to 47, and the no-bundled-motion test now
uses Treadmill - a permanent COVERAGE.md exclusion - since Bench Press
exists. 48 tests green; watch target builds. Coverage handoff complete -
TODO-coverage.md retired.

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

Workouts/Resources/ExerciseMotions/Dumbbell Fly.motion.json

@@ -0,0 +1,39 @@
+{
+  "name": "Dumbbell Fly",
+  "primary": 2,
+  "camera": {"yaw": 90},
+  "working": ["arm_r", "arm_l"],
+  "props": [
+    {"type": "scene", "shapes": [
+      {"kind": "line", "pts": [[148, 124], [172, 124]], "w": 8, "depth": 40},
+      {"kind": "line", "pts": [[154, 129], [154, 150]], "w": 4},
+      {"kind": "line", "pts": [[166, 129], [166, 150]], "w": 4}
+    ]},
+    {"type": "dumbbell", "at": "hand_r"},
+    {"type": "dumbbell", "at": "hand_l"}
+  ],
+  "frames": [
+    {
+      "hold": 0.5, "tween": 1.0,
+      "root": {"pos": [160, 116], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 8, "head": 0,
+      "shoulder_r": 88, "elbow_r": 12,
+      "shoulder_l": 88, "elbow_l": 12,
+      "hip_r": {"flexion": 78, "abduction": 10}, "knee_r": 82, "ankle_r": 5,
+      "hip_l": {"flexion": 78, "abduction": 10}, "knee_l": 82, "ankle_l": 5,
+      "pins": {"foot_r": [142, 148], "foot_l": [178, 150]}
+    },
+    {
+      "hold": 0.5, "tween": 1.3,
+      "root": {"pos": [160, 116], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 8, "head": 0,
+      "shoulder_r": {"flexion": 16, "abduction": 84}, "elbow_r": 22,
+      "shoulder_l": {"flexion": 16, "abduction": 84}, "elbow_l": 22,
+      "hip_r": {"flexion": 78, "abduction": 10}, "knee_r": 82, "ankle_r": 5,
+      "hip_l": {"flexion": 78, "abduction": 10}, "knee_l": 82, "ankle_l": 5,
+      "pins": {"foot_r": [142, 148], "foot_l": [178, 150]}
+    }
+  ]
+}