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/Pec Deck.info.md

@@ -0,0 +1,40 @@
+# Pec Deck
+
+The machine chest fly — arms sweep together in front of the chest along
+the machine's fixed arc.
+
+- **Category:** Main circuit
+- **Type:** Machine-based chest fly
+- **Targets:** Chest, front delts
+- **Prescription:** 4 × 10
+
+## Setup
+
+Adjust the seat so the handles sit at chest height with your upper arms
+level. Back flat on the pad, feet planted, a soft bend fixed in the
+elbows.
+
+## Execution
+
+1. Sweep both arms together in a wide arc until the handles meet in
+   front of the chest.
+2. Squeeze the chest hard for a beat at the middle.
+3. Open back up with control until you feel a full chest stretch.
+
+## Cues
+
+- Elbow angle never changes — the chest swings the arms.
+- Shoulders stay back against the pad; they don't roll forward at the
+  squeeze.
+- Slow the return; the stretch half of the rep counts.
+
+## Common Mistakes
+
+- Setting the seat so low the handles sit at the shoulders.
+- Shoulders rounding forward to chase extra range.
+- Letting the stack yank the arms open.
+
+## Progression
+
+Add a plate once every rep meets in the middle with a one-second
+squeeze; the Dumbbell Fly trades the guided path for free control.