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/smoke-checklist.md

@@ -37,3 +37,6 @@
 35. Pausing saves a checkpoint: returning to the menu and choosing Continue resumes elapsed time, NPCs, incidents, door/flashlight state and campaign position.
 36. Settings difficulty changes spawn pacing/compliance/report strictness while escalation rules stay the same; Help filters controls and shows the venue policy.
 37. The F debug overlay lists the next eligible events; recovery events and recently played scripted events behave as authored.
+38. Master/SFX/ambience volume settings clamp at 0/1 and persist; Reduce motion disables head bob; the captions toggle persists.
+39. The 24-NPC budget smoke stays inside its frame budget; coats/dresses do not show obvious leg clipping in a normal walk.
+40. Help remains readable with the largest HUD font scale, and the engine matrix (4.3 CI / 4.7.2 local) is used for verification.