@swc/core fails to load on wasm32 runtimes: @swc/core-wasm32-wasi is referenced by the loader but never published #12466

Describe the feature

The napi-rs loader in packages/core/binding.js tries require('@swc/core-wasm32-wasi') as its last fallback, but that package has never been built or published. On any wasm32 runtime, require('@swc/core') therefore fails with Failed to load native binding before the @swc/wasm fallback in index.js gets a chance to run.

Why it matters

In-browser Node runtimes such as WebContainers and Strapkit run everything on wasm32-wasi, so there is no native binary to load. Anything that pulls in @swc/core is currently broken in those environments, including:

• @swc/cli builds (swc src -d dist)
• @swc/jest
• webpack's swc-loader
• @vitejs/plugin-react-swc

Each runtime ends up carrying its own workaround. rolldown, oxc and rspack all publish a wasi binding through the same napi-rs pipeline, so swc is the odd one out here.

To reproduce

1. Open a project that depends on @swc/core in a wasm32-wasi Node runtime (e.g. WebContainers).
2. Run node -e "require('@swc/core')".
3. It throws Failed to load native binding.

Expected behavior

@swc/core loads on wasm32 runtimes via a published @swc/core-wasm32-wasi package, as binding.js already expects.

Proposed fix

Build and publish the wasi binding through the existing napi-rs pipeline:

• Add wasm32-wasip1-threads to napi.targets in packages/core/package.json, so napi artifacts picks up the wasi files and napi prepublish adds @swc/core-wasm32-wasi to optionalDependencies. cpu: ["wasm32"] keeps it off native installs.
• Add packages/core/scripts/npm/wasm32-wasi/, mirroring the other per-target npm dirs.
• Add a build matrix entry to publish-npm-package.yml. It only needs to build for @swc/core (the other packages skip it and the artifact upload tolerates that), and the upload glob needs to also grab the napi-generated wasi-worker* files.

The swc CLI binary can be skipped for this target; a wasi CLI build is a separate discussion.

Additional context

I have a working branch with these changes: #12064. But It's probably easier for the maintainers to just add it themselves.

Babel plugin or link to the feature description

No response

Additional context

No response