- Replace thiserror derive with manual Display + core::error::Error impl
- Zero runtime dependencies (was: thiserror)
- Use (v + 0.5) as u32 instead of f64::round() for no_std compat
- Tighten compression_ratio_sanity threshold (< 100 bytes, was < 1000)
- Add errors_when_precision_too_small_for_alphabet test
- Simplify no_std section in README