Add a shader language — GLSL, HLSL or WGSL — next to CUDA and Metal

## What is missing

ripwire already reads CUDA, where kernel launch sites become call edges, and Metal. It does not read
GLSL, HLSL or WGSL. In a game engine, a renderer or a WebGPU app, the host code therefore appears to
call into nothing, and the CPU/GPU contract — bindings, uniform layouts, entry points — stays
invisible to an agent. The job is one shader language: measure the grammar candidates' parse rates
on real shader corpora, pick the best, extract functions, bindings and entry points, and disclose
the blind spots.

## The evidence

The grammar survey is already done and verified: **four tree-sitter grammars**, each recorded with
its license, pinned commit, ABI, external scanner and parent grammar. The measurement order is GLSL,
then HLSL, then WGSL. The corpora are named: glslang, DirectXShaderCompiler, Unity's Graphics
repository and wgpu.

The design decisions are framed rather than left open — a new `Lang` versus riding a C-family one
(with the CUDA and Metal precedents either way), entry points and stages, bindings and uniforms as
symbols, the include and import story (GLSL's include extensions, HLSL's `#include`, WGSL's lack of
any import, and naga_oil's `#import`), and built-in names that collide with user functions.

## Size

**Large** end to end, but the three languages are independent lanes and the first step is small:

- **The STEP 0 survey** (parse rates per grammar per corpus): small, and worth posting as a draft
pull request before starting extraction.
- **One language** with definitions, bindings and a red-first gate: medium to large.
- **Include and import edges:** a follow-up.

## Prerequisites

Shader experience — writing or reading GLSL, HLSL or WGSL and knowing how an engine binds resources
— plus C++23 and CMake, tree-sitter basics, and a shader corpus to measure on. The prompt names
public ones.

## Where to start

`prompts/help-wanted/shader-languages.md` follows `prompts/add-a-language.md` and carries the
verified grammar survey, the corpora, the design notes above, the traps and the acceptance criteria.
Like every prompt in `prompts/`, **it ends by writing a plan and stopping** — a maintainer agrees
the plan before any code is written.

Comment here to claim it, naming the language being taken.

Read prompts/help-wanted/shader-languages.md and its referenced prompts/add-a-language.md first. Measure the four surveyed grammar candidates against the named glslang, DirectXShaderCompiler, Unity Graphics, and wgpu corpora in the stated order. Done for the first step means posting the parse-rate results and a plan as a draft pull request, then stopping for maintainer agreement.

Written by the indexing model from the issue text.