chore: fix Phase 2 formatting and clippy lints
- Fix rustfmt line-breaking issues across multiple function signatures
- Add Default impl for RealDnsResolver (clippy::new_without_default)
- Use handle.is_ascii() instead of char iterator (clippy::needless_character_iteration)
- Remove redundant guard in pattern match (clippy::redundant_guards)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>