feat: add WASM bindings (txm-wasm)

[mex7xx]

What

Adds WebAssembly / JavaScript bindings for TXM, mirroring the existing bindings/py/ pattern. Exposes a single function:

#[wasm_bindgen]
pub fn render(input: &str) -> Result<String, JsValue>

Why

WASM bindings let TXM be used from Node.js, browsers, and any JS runtime — useful for terminal UIs, editors, and tools that want inline LaTeX math rendering without a subprocess.

Files

• bindings/wasm/src/lib.rs — 7-line wasm_bindgen wrapper around txm::render
• bindings/wasm/Cargo.toml — standalone [workspace], path-dep on txm with default-features = false (keeps fancy/ratatui out of the wasm build)
• bindings/wasm/README.md — Node.js build + usage instructions

Design decisions

• Mirrors bindings/py/ — same standalone-workspace + path-dep pattern, same render -> Result<String, Error> API shape
• default-features = false — the fancy (yansi) and ratatui features aren't useful in wasm; we only need the plain-text render path
• No core crate changes — purely additive, can't break existing CLI / PyPI / nix pipelines

Verified locally

$ wasm-pack build bindings/wasm --target nodejs
$ node -e "const {render} = require('./pkg/txm_wasm.js'); console.log(render('\\\\int_0^\\\\infty e^{-x^2}\\\\,dx'))"

∞
⎛   -x²
⎜  e    dx
⎠
0

Suggested CI (couldn't push — fork token lacks workflow scope)

If you'd like CI for the wasm build, here's a ready-to-add .github/workflows/wasm.yml:

name: WASM
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7
      - uses: actions-rust-lang/setup-rust-toolchain@v1.17.0
        with:
          targets: wasm32-unknown-unknown
      - uses: jetli/wasm-pack-action@v0.4.0
      - run: wasm-pack build bindings/wasm --target nodejs
      - name: Smoke test
        run: |
          node -e "
          const { render } = require('./bindings/wasm/pkg/txm_wasm.js');
          const out = render('E = mc^2');
          if (!out.includes('mc')) { console.error(out); process.exit(1); }
          console.log('OK');
          "

Happy to adjust naming (txm-wasm mirrors txm-py), targets, or structure to match your preferences.

[DuskyElf]

why are the tests in the CI and not part of the wasm package ?

[mex7xx]

sorry, too much vibe coding - agent couldn't access .github/workflows

[Copilot]

Pull request overview

Adds a new bindings/wasm/ crate to expose TXM rendering via WebAssembly/JavaScript using wasm-bindgen, following the existing standalone-workspace + path-dependency pattern used by bindings/py/.

Changes:

• Introduces txm-wasm crate with a single render(&str) -> Result<String, JsValue> export calling into txm::render.
• Adds Node-focused build and usage documentation for the wasm package.
• Adds a GitHub Actions workflow to build the wasm bindings and run a minimal Node smoke test.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
bindings/wasm/src/lib.rs	Adds the wasm-bindgen wrapper API over txm::render.
bindings/wasm/README.md	Documents building with wasm-pack and Node usage examples.
bindings/wasm/Cargo.toml	Defines the txm-wasm crate and its path dependency on txm with default-features = false.
bindings/wasm/Cargo.lock	Locks dependencies for the standalone wasm workspace.
.gitignore	Ignores wasm-pack build output directory.
.github/workflows/wasm.yml	Adds CI build + Node smoke test for wasm bindings.

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