chore: add pre-commit hooks and fix clippy warnings
- Add pre-commit configuration with cargo fmt and clippy checks
- Remove obsolete .tangled/workflows/deploy.yaml
- Fix all clippy warnings:
- Replace redundant closures with function references
- Use .first() instead of .get(0)
- Use .or_default() instead of .or_insert_with(Vec::new)
- Use .unsigned_abs() instead of .abs() as u32
- Use .div_ceil() instead of manual ceiling division
- Simplify iterator patterns with .flatten()
- Remove needless return statements
- Replace useless format!() with .to_string()
- Use array literals instead of vec![] where appropriate
- Remove redundant field names in struct initialization
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Co-Authored-By: Claude <noreply@anthropic.com>