Publish an official wasip1 (WASI) build artifact of tsgo

@jakebailey がすでに取り組んでいます。

2026年7月15日 から。

### Request

Please consider publishing an official `GOOS=wasip1 GOARCH=wasm` build artifact of `tsgo` alongside the native platform binaries (npm `@typescript/*` platform packages / GitHub release assets).

### Context

We embed JavaScript tooling in WebAssembly (WASI) environments and evaluated running the TypeScript 7 compiler there. Building from source works today with no patches:

```
GOOS=wasip1 GOARCH=wasm go build ./cmd/tsgo # at tag typescript/v7.0.2, go1.26.4
```

- One command, ~40s build, ~48.6 MB core module.
- Runs under wasmtime (preview1): diagnostics are byte-identical to the native binary on our test projects, exit codes preserved.
- Single-threaded as expected for this target (~12× native wall-clock in our samples — still practical for small/medium projects).
- Known limitation we observed: wasm32's 4 GiB memory ceiling prices out very large programs (a `type-fest`-scale check needed ~6.6 GB natively).

### Why an official artifact

The build is trivially reproducible, but an official artifact would give WASI/browser-adjacent consumers a supported, versioned binary instead of each project maintaining its own build pipeline, and would make regressions on this target visible to CI here rather than downstream.

Happy to share our verification receipts (diagnostic byte-comparisons vs the native binary) if useful.