Match forward search dispatch flags together

[fyrsta7]

Summary

This rewrites the forward hybrid DFA search dispatch in find_fwd as a single match over the prefilter and earliest-search flags.

Why this can improve performance

find_fwd dispatches to four monomorphized search paths depending on whether a prefilter is present and whether earliest mode is enabled. Matching on both booleans together keeps the dispatch compact while preserving the same specialized calls for each case.

Validation

• git diff --check
• cargo check --manifest-path regex-automata/Cargo.toml --lib

Benchmark

Current machine, Rust release microbenchmark, 9 samples, median:

Benchmark	Base	This change	Delta
Hybrid regex find_iter over a high-match haystack	24,418.079 ns/op	23,388.972 ns/op	4.21% faster