Full Go time.ParseDuration compatibility for Python
Features:
- Parse Go-style duration strings: 1m, 2h, 2h30m, -8h
- Support all Go time units: ns, us, µs, ms, s, m, h
- Fractional numbers: 1.5h, 30.918s
- Edge cases: 0, +1h, 1h0m0s
- 32 comprehensive tests
- README-based testing via make test