Prettier's aggressive line-splitting (printWidth 100, single quotes) didn't
match the project's existing compact code style. Switch to Biome which
provides formatting + linting in one tool with better chain-call handling.
- Remove prettier, add @biomejs/biome
- Configure biome: double quotes, lineWidth 150, recommended lint rules
- Update lefthook pre-commit to use `biome check`
- Full codebase format pass with new config
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>