27088ab810
Switches unitig processing to a lazy, fallible `try_for_each_unitig` API across partitioner layers, reducing intermediate allocations and enabling proper error propagation. Refactors de Bruijn graph traversal into a two-pass algorithm with explicit node flags, named constants, and diagnostic logging. Introduces parallel chain processing and staged performance profiling for the unitig command, and adds a memory-efficient `FromIterator` implementation for packed nucleotide sequences.