The former WGSL-only wgsl-shader example is renamed to shader-material, gains matching GLSL shader chunks, and runs on both WebGL2 and WebGPU. The example is no longer hidden so it appears in the shaders category.

Changes:

• Rename example and shader assets to shader-material, using the same chunk naming pattern as other shader examples (*.shader.glsl.vert, *.shader.wgsl.vert, etc.).
• Supply vertexGLSL / fragmentGLSL alongside WGSL; use aPosition / aUv0 attributes aligned with primitive meshes.
• Remove WEBGL_DISABLED, HIDDEN, and the runtime WebGPU requirement.
• Add sidebar thumbnails for shaders/shader-material.

Examples:

• Renamed: examples/src/examples/shaders/shader-material.example.mjs (from wgsl-shader.example.mjs).
• New GLSL: shader-material.shader.glsl.vert, shader-material.shader.glsl.frag.
• WGSL: shader-material.shader.wgsl.vert, shader-material.shader.wgsl.frag.

Note: Direct links to the old iframe path shaders_wgsl-shader will need updating to shaders_shader-material.