feat: add GLSL support via tree-sitter-glsl (#685)

[KadirKess]

Summary

Add GLSL shader file indexing (.glsl, .vert, .frag, .comp, .geom, .tesc, .tese) — functions, structs, and intra-file calls are extracted so you can navigate and query shader code alongside the rest of the project.

Closes #685

Changes

• Vendor tree-sitter-glsl.wasm (ABI-15) in src/extraction/wasm/
• Add glslExtractor with:
  • resolveBody — GLSL function_definition exposes compound_statement as a plain named child, not a body field
  • visitNode — intercepts declaration nodes containing nested struct_specifier so structs aren't swallowed by the variable extraction path
• Register all 7 shader extensions in the extension map, WASM grammar map, and display name map
• Add 'glsl' to the LANGUAGES const array in types.ts
• Add extraction tests covering language detection, function extraction, struct extraction, and call extraction
• Update README supported languages table and summary line
• Update CHANGELOG

Testing

All 5 new GLSL extraction tests pass:

• Language detection for all 7 shader extensions
• isLanguageSupported('glsl') and getSupportedLanguages() include 'glsl'
• Function extraction (void main(), typed vec3 computeNormal(...))
• Struct extraction (struct Light { ... })
• Intra-file call extraction (square() → unresolved reference)

tsc --noEmit passes cleanly.

[treytracedit-lab]

C++