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 Bench Press.motion.json

@@ -0,0 +1,40 @@
+{
+  "name": "Dumbbell 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": "dumbbell", "at": "hand_r"},
+    {"type": "dumbbell", "at": "hand_l"}
+  ],
+  "frames": [
+    {
+      "hold": 0.4, "tween": 0.9,
+      "root": {"pos": [150, 116], "pitch": -90},
+      "spine": [0, 0],
+      "neck": 8, "head": 0,
+      "shoulder_r": 12, "elbow_r": 105,
+      "shoulder_l": 12, "elbow_l": 105,
+      "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": [90, 104], "hand_l": [98, 106]}
+    },
+    {
+      "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": [66, 57], "hand_l": [72, 59]}
+    }
+  ]
+}