rewrite in rust

[anonrig]

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