refactor: modular architecture with unified error handling and DashMap concurrency
- Break monolithic records.rs into commands/, output/, parsing/ modules
- Add lib.rs with shared types (AppError, Car, BestCarRecord, etc.)
- Replace Arc<Mutex<HashMap>> with DashMap for concurrent access
- Add unified AppError enum with thiserror
- Add configurable CLI paths (--my-cars, --cars-db, --times-dir, --tracks-db)
- Add serde deserialization for Car struct
- Add CSV escaping for fields with commas/quotes/newlines
- Fix track name splitting: split_once -> rsplit_once for _a handling
- Add integration tests, proptest property-based tests, and unit tests
- Add rustfmt.toml configuration
- Update documentation (API, ARCHITECTURE, DATA_STRUCTURES, README)
Jan-Peter von Hunnius
a9a46ee551