Ship the 0.9.0 production-quality milestone

Add mixer/accessibility settings, caption/reduce-motion hooks, audio volume
clamping, a 24-NPC performance smoke and shortened coat/dress stride for hem
clipping. Record the explicit Godot 4.3-CI/4.7-local matrix and the 0.9
production scope. Headless 250/250, Python 94/94, 24-NPC budget smoke passes.

docs/gameplay.md

@@ -4,7 +4,7 @@ The complete design rationale also lives in [`PLAN.md`](../PLAN.md); this page k
 
 ## Game Overview
 
-A typical shift lasts 10–15 minutes. The player:
+A typical shift lasts 10–15 minutes. The first-person camera stays at the gameplay height of 1.7 m; the concept frames use a lower ~1.55 m reference camera, but gameplay readability and body-camera framing take priority. The player:
 
 1. Watches the entrance, steps, queue, and surrounding sidewalk.
 2. Determines why each person is approaching.