chore: satisfy current Biome checks

[thekidnamedkd]

Context

While preparing the OMP integration, I noticed the current Biome config flags a small set of existing source/test files. This PR keeps that cleanup separate from the OMP parser work so either PR can be reviewed and merged independently.

What changed

• Applies current Biome autofixes for Node builtin imports, template literals, parseInt radix, import ordering, and formatting.
• Replaces the remaining explicit any annotations in test/e2e utilities with unknown or narrow local types.
• Does not change parser behavior, runtime behavior, package metadata, docs, or fixtures.

Verification

• npm run lint
• corepack pnpm@10 run build
• corepack pnpm@10 test
• corepack pnpm@10 run check

Review notes

This is intentionally separate from #78. It can be merged before or after the OMP support PR.

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Summary by cubic

Clean up to satisfy current Biome rules across sources and tests. No behavior changes; lint, build, and tests all pass.

• Refactors
  • Applied Biome autofixes: node: built-in imports, template literals, parseInt radix, import order, and formatting.
  • Tightened typings and error handling in tests/e2e and utils (use unknown guards, narrower types); simplified custom error classes.
  • Normalized string construction and console output; no parser or runtime changes.

^{Written for commit 74fb017. Summary will update on new commits.}