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.info.md

@@ -0,0 +1,38 @@
+# Dumbbell Fly
+
+The chest isolation — arms sweep from wide open to over the chest in a
+hugging arc, elbows softly fixed.
+
+- **Category:** Main circuit
+- **Type:** Free-weight chest fly (dumbbells)
+- **Targets:** Chest, front delts
+- **Prescription:** 3 × 10–15, light and controlled
+
+## Setup
+
+Lie on the flat bench with light dumbbells pressed over the chest, palms
+facing each other, a slight fixed bend in the elbows.
+
+## Execution
+
+1. Open the arms in a wide arc until you feel a full chest stretch —
+   hands about level with the chest, never below the shoulders' comfort.
+2. Keep the elbow angle unchanged the entire way.
+3. Sweep back up as if hugging a barrel, squeezing the chest together.
+
+## Cues
+
+- It's an arc, not a press — the elbows never bend and extend.
+- Go light; the stretch does the work, not the load.
+- Stop the descent the moment the chest stretch peaks.
+
+## Common Mistakes
+
+- Bending the elbows on the way down and pressing back up.
+- Dropping too deep and straining the shoulders.
+- Using bench-press weights.
+
+## Progression
+
+Slow the lowering phase and pause in the stretch; the Pec Deck offers
+the same motion with the path guided.