feat: add benchmark pipeline, expose APIs, and enforce strict paths

Introduces a Make-based orchestration for simulating, indexing, merging, filtering, and verifying k-mer counts and presence. Exposes internal builder and iterator APIs publicly, enforces mandatory leading slashes for predicate patterns, registers the `obitaxonomy` crate, and updates tooling configurations alongside documentation.

src/obidebruinj/src/debruijn.rs

@@ -3,6 +3,7 @@ use crossbeam_channel;
 use hashbrown::HashMap;
 use obikseq::k;
 use obikseq::{CanonicalKmer, Sequence, Unitig};
+#[cfg(not(any(test, feature = "test-utils")))]
 use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
 use std::cell::RefCell;
 use std::fmt;