Add shadertoy-server example for WebGL shader rendering (#226)

Introduces a new MCP App example that renders ShaderToy-compatible GLSL
fragment shaders in real-time using WebGL 2.0 and ShaderToyLite.js.

Features:
- Standard ShaderToy uniforms (`iTime`, `iResolution`, `iMouse`, etc.)
- Multi-pass rendering with buffers A-D for feedback effects
- Shader compilation error overlay

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

.prettierignore

@@ -2,3 +2,4 @@ examples/basic-host/**/*.ts
 examples/basic-host/**/*.tsx
 examples/basic-server-*/**/*.ts
 examples/basic-server-*/**/*.tsx
+**/vendor/**