fix: lower void conditionals as statements

[CooperSheroy]

Summary

Fixes #33 by lowering void-position conditional expressions as statements instead of emitting a void-valued IR ternary.

This covers concise void-returning arrow bodies such as:

const pick = () => cond ? a() : b();

and also statement-position conditionals, preserving lazy branch evaluation while respecting the existing IR invariant that ternary is value-typed.

Validation

• pnpm install --frozen-lockfile
• pnpm build
• pnpm exec vitest run tests/harness/differential.test.ts -t 2352-void-coercions
• pnpm lint
• git diff --check

Note: this host is on Node v22.22.2, so pnpm printed the repository engine warning for Node >=24. The commands above still completed successfully.

[vercel]

@CooperSheroy is attempting to deploy a commit to the Vercel Labs Team on Vercel.

A member of the Team first needs to authorize it.