Build fails with `[UNRESOLVED_ENTRY] nitro/dist/presets/bun/runtime/bun` when a custom `resolve.extensions` is set

[AhmedElBanna80]

Found running the official Next.js e2e test suite against vinext (vinext 1.0.0-beta.8, Next.js 16.2). Error line is from the suite's own output.

Fixture: test/e2e/app-dir/resolve-extensions

Symptom (build): [UNRESOLVED_ENTRY] nitro/dist/presets/bun/runtime/bun. A fixture-level custom resolve.extensions appears to shadow the nitro bun preset's own entry resolution, so the preset runtime entry no longer resolves.

Repro: an app that overrides resolve.extensions, built through the nitro preset: 'bun'.