Help docs: verified-checkmark gif + refreshed cross-post tutorial

Reflect overlaps rework: per-result flags in screenshots + text

Re-formatted tutorials, default reported metrics to Overlaps

Restructure About, share cite/contribute sections, humanize tutorials, default reported metrics to Overlaps

Open reported metrics in Overlaps view by default

Rework Help/About: tutorials, signal docs, contribute/cite sharing, terminology, screenshots; default researcher view to full result set

Add Help: intro tour, tutorials, stakeholder guides, citation info, footer