Plugin README, marketplace README, and CONTRIBUTING.md were committed
with pre-v1.6.0 content. Syncs all documentation with the actual v1.6.0
release: adds /ultraresearch-local section, updates agent count (19),
command count (3), pipeline diagram, examples, and architecture tree.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>