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/Rear Delt Fly.motion.json

@@ -0,0 +1,37 @@
+{
+  "name": "Rear Delt Fly",
+  "primary": 2,
+  "camera": {"yaw": 270},
+  "working": ["arm_r", "arm_l"],
+  "props": [
+    {"type": "scene", "shapes": [
+      {"kind": "line", "pts": [[160, 64], [160, 120]], "w": 16, "z": -14, "depth": 6},
+      {"kind": "line", "pts": [[135, 131], [185, 131]], "w": 10, "depth": 12},
+      {"kind": "line", "pts": [[160, 136], [160, 150]], "w": 6}
+    ]},
+    {"type": "pad", "at": "hand_r", "angle": 90, "halfLen": 9, "w": 5},
+    {"type": "pad", "at": "hand_l", "angle": 90, "halfLen": 9, "w": 5}
+  ],
+  "frames": [
+    {
+      "hold": 0.5, "tween": 1.1,
+      "root": {"pos": [160, 116]},
+      "spine": [0, 0],
+      "neck": 0,
+      "shoulder_r": {"flexion": 85, "abduction": 6}, "elbow_r": 15,
+      "shoulder_l": {"flexion": 85, "abduction": 6}, "elbow_l": 15,
+      "hip_r": 78, "knee_r": 62,
+      "hip_l": 78, "knee_l": 62
+    },
+    {
+      "hold": 0.5, "tween": 1.2,
+      "root": {"pos": [160, 116]},
+      "spine": [0, 0],
+      "neck": 0,
+      "shoulder_r": {"flexion": 12, "abduction": 84}, "elbow_r": 15,
+      "shoulder_l": {"flexion": 12, "abduction": 84}, "elbow_l": 15,
+      "hip_r": 78, "knee_r": 62,
+      "hip_l": 78, "knee_l": 62
+    }
+  ]
+}