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

CHANGELOG.md

@@ -1,5 +1,7 @@
 **July 2026**
 
+The exercise library more than doubles — deadlifts, squats, lunges, bench presses, dumbbell work, pull-ups, and the cable stations — each with its own animated form guide.
+
 Machine form guides now slowly circle around the figure too — seats, cables, and pads turn with the body, showing every exercise from all sides.
 
 Form guides are now viewed from a slight elevation, with an exercise mat under the figure that turns with the camera.