130: Bootstrap support for phylogenetic trees

[glstott]

Addresses feature request #130

Summary

• Adds Phylogeny bootstrap support for sequence-derived trees, including configurable replicate count, optional early stop when support values stabilize, decimal precision, progress display, and cancel behavior.
• Computes bootstrap support in a worker-backed SNP pseudoalignment / neighbor-joining pipeline, stores support metadata in the session, and applies support values to internal tree branches.
• Updates Phylogeny branch label handling so bootstrap support values can be shown/hidden, formatted as percentages, resized with the branch label font-size control, and restored after session reload.
• Adds validation and unavailable-state messaging for unsupported inputs such as Newick-only, matrix-only, modified, missing-sequence, or unaligned-sequence trees.
• Adds unit coverage for bootstrap split/support utilities and a Cypress journey covering calculation, formatting, unavailable inputs, early-stop behavior, and session round-trip persistence.