Replaces the synchronous sequential loop with a multi-threaded pipeline using `WorkerPool` and custom stage macros. Shared mutable state is wrapped in `Arc<Mutex<>>` for thread-safe updates, while pipeline errors are centralized via `Arc<Mutex<Option<String>>>` to propagate failures before thread join.
Introduce the `obipipeline` dependency and refactor merge and partition logic to leverage parallel execution. Update `merge_partitions` to use rayon with dynamic memory budgeting and concurrency control via a pilot run. Refactor Pass 1 to concurrently read unitigs, filter kmers through a shared `LayeredMap`, and populate the graph safely. Simplify diagnostics to report total kmer counts and replace manual flags with graph length validation.
Introduce a `peak_rss_bytes()` utility for accurate per-phase RAM measurement. Replace the genome-length heuristic with a dynamic seed expansion ratio based on actual RSS delta. Explicitly drop the `GraphDeBruijn` instance before MPHF construction to prevent resource contention and ensure proper memory management.
Eric Coissac