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/getting-started.md

@@ -2,7 +2,7 @@
 
 ## Setup
 
-1. Download the Godot 4.3+ editor (official build) and put `godot` on your PATH. CI pins 4.3; local development is verified with 4.7.2.
+1. Download the Godot 4.3+ editor (official build) and put `godot` on your PATH. The supported policy is an explicit matrix: CI/release baseline 4.3, local development verified with 4.7.2. Engine upgrades require import, headless, screenshot and Desktop HQ smoke checks before changing the baseline.
 2. Open or run the project from this directory.
 
 ## Run and Test
@@ -38,7 +38,7 @@ godot --headless --path . --script res://src/test/smoke_plan_verbs.gd
 # Prop-collision smoke (windowed): guard stops at a bench, guest routes around it
 godot --path . --script res://src/test/smoke_props.gd
 
-# NPC budget smoke: 16 full-rig avatars against the documented frame budget
+# NPC budget smoke: 24 full-rig avatars against the documented frame budget
 godot --headless --path . --script res://src/test/smoke_npc_budget.gd
 
 # Movement smoke (windowed): steps, precision walk, footsteps and landing