Initial commit: Unity mesh painter project

Unity 6000.3 (URP) project with live mesh painting in play mode.

- MeshPainter.cs: paint a SkinnedMesh with the mouse, seamless across
  UV islands via 3D-space painting, GPU and CPU backends (switchable),
  edge-padding/dilation against bilinear seam bleed
- FrameRateLimiter.cs: simple frame rate limiting component
- MeshPaintBrush / MeshPaintDilate shaders for the GPU paint path
- Unity-specific .gitignore and .gitattributes

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ProjectSettings/AudioManager.asset

@@ -0,0 +1,19 @@
+%YAML 1.1
+%TAG !u! tag:unity3d.com,2011:
+--- !u!11 &1
+AudioManager:
+  m_ObjectHideFlags: 0
+  serializedVersion: 2
+  m_Volume: 1
+  Rolloff Scale: 1
+  Doppler Factor: 1
+  Default Speaker Mode: 2
+  m_SampleRate: 0
+  m_DSPBufferSize: 1024
+  m_VirtualVoiceCount: 512
+  m_RealVoiceCount: 32
+  m_SpatializerPlugin: 
+  m_AmbisonicDecoderPlugin: 
+  m_DisableAudio: 0
+  m_VirtualizeEffects: 1
+  m_RequestedDSPBufferSize: 0