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.

src/test/smoke_npc_budget.gd

@@ -9,7 +9,7 @@ extends SceneTree
 const NpcAvatar := preload("res://src/game/npc_avatar.gd")
 const NpcProfile := preload("res://src/core/npc_profile.gd")
 const Rules := preload("res://src/core/rules.gd")
-const COUNT := 16
+const COUNT := 24
 const WARMUP_FRAMES := 60
 const SAMPLE_FRAMES := 180
 const BUDGET_MS := 50.0