Replaces `rayon` parallel iteration across index, rebuild, reindex, and select modules with a custom `PartitionRunner`. This introduces NUMA-aware task distribution with CPU pinning and round-robin scheduling, eliminating `Arc`, `Mutex`, and atomic synchronization primitives in favor of a flat, pre-spawned worker architecture. Error handling is simplified via `.map_err()` and the `?` operator, while progress bar updates are decoupled into dedicated callbacks.
This commit restructures the partitioner crate by extracting shared utilities and the `ColBuilder` enum into a new `common` module. It introduces a multi-phase `graph_pipeline` for constructing and materializing De Bruijn graphs, replacing manual graph construction in `index_layer`, `merge_layer`, and `rebuild_layer`. All layer workflows now use centralized `build_graph` and `materialize_layer` abstractions, with standardized error context strings for improved diagnostics.
Eric Coissac