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/Crunch.motion.json

@@ -0,0 +1,29 @@
+{
+  "name": "Crunch",
+  "primary": 2,
+  "working": ["spine"],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 0.8,
+      "root": {"pos": [166, 146], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 12, "head": 0,
+      "shoulder_r": 155, "elbow_r": 140,
+      "shoulder_l": 155, "elbow_l": 140,
+      "hip_r": 75, "knee_r": 85, "ankle_r": 5,
+      "hip_l": 75, "knee_l": 85, "ankle_l": 5,
+      "pins": {"foot_r": [205, 148], "foot_l": [209, 150]}
+    },
+    {
+      "hold": 0.6, "tween": 1.0,
+      "root": {"pos": [166, 144], "pitch": -90},
+      "spine": [14, 34],
+      "neck": 30, "head": 0,
+      "shoulder_r": 150, "elbow_r": 140,
+      "shoulder_l": 150, "elbow_l": 140,
+      "hip_r": 75, "knee_r": 85, "ankle_r": 5,
+      "hip_l": 75, "knee_l": 85, "ankle_l": 5,
+      "pins": {"foot_r": [205, 148], "foot_l": [209, 150]}
+    }
+  ]
+}