rewrite in rust

## Benchmark results Measured on the same 11-URL corpus as the README (808 bytes total). | Implementation | `parse` | `can_parse` | |---|---|---| | **C++ backend** (README baseline) | 2.016 µs — 382 MiB/s | 1.212 µs — 636 MiB/s | | **Pure Rust** (stable, no feature flags) | **1.503 µs — 513 MiB/s** | **0.454 µs — 1 697 MiB/s** | | **Pure Rust + `nightly-simd`** (`std::simd`, nightly only) | **1.457 µs — 529 MiB/s** | 0.511 µs — 1 508 MiB/s | | servo `url` crate | 3.562 µs — 216 MiB/s | — | - `parse` is **25% faster** than the C++ backend (stable), **28% faster** with nightly SIMD - `can_parse` is **2.7× faster** than the C++ backend with zero heap allocations for any input - Both beat the servo `url` crate: `parse` by **2.4×**, `can_parse` by a wide margin