feat(sfx): play paint_apply sound when a material is painted

Registers a paintApply SFX (with rate/volume jitter + a 60ms gap so rapid
multi-face painting doesn't machine-gun), wires the sfx:paint-apply bus
event, and emits it from the material-paint click chokepoint in the
selection manager (fires on apply, not hover/preview). Adds the audio
asset to the editor app's public resources.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/editor/src/components/editor/selection-manager.tsx

@@ -1157,6 +1157,7 @@ export const SelectionManager = () => {
       }
 
       interaction.apply()
+      sfxEmitter.emit('sfx:paint-apply')
       if (activePreview?.key === interaction.key) {
         activePreview = null
       } else {

packages/editor/src/lib/sfx-bus.ts

@@ -16,6 +16,7 @@ type SFXEvents = {
   'sfx:snapshot-capture': undefined
   'sfx:menu-hover': undefined
   'sfx:menu-click': undefined
+  'sfx:paint-apply': undefined
 }
 
 /**
@@ -45,6 +46,7 @@ export function initSFXBus() {
   sfxEmitter.on('sfx:snapshot-capture', () => playSFX('snapshotCapture'))
   sfxEmitter.on('sfx:menu-hover', () => playSFX('menuHover'))
   sfxEmitter.on('sfx:menu-click', () => playSFX('menuClick'))
+  sfxEmitter.on('sfx:paint-apply', () => playSFX('paintApply'))
 }
 
 /**

packages/editor/src/lib/sfx-player.ts

@@ -100,6 +100,15 @@ export const SFX: Record<string, SFXConfig> = {
     volumeRange: [0.5, 0.6],
     panJitter: 0.1,
   },
+  // Fired when a material is applied to a surface in paint mode. Painting can
+  // fire in quick succession across faces, so keep variation + a small gap.
+  paintApply: {
+    src: '/audios/sfx/paint_apply.mp3',
+    rateRange: [0.95, 1.05],
+    volumeRange: [0.85, 1.0],
+    panJitter: 0.12,
+    minIntervalMs: 60,
+  },
 } as const
 
 export type SFXName = keyof typeof SFX