docs: lighten GitHub glyph so it reads against the dark theme

docs: real GitHub + YouTube glyphs in nav table; IA circle logo for Website

docs: rewrite org card around new website positioning; drop roster/metrics/stack

docs: revert tagline to 'An AI lab for actuarial science' (HF brand voice)

docs: institutional positioning, /engagement -> /commitments, add Lab + GitHub + YouTube

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

initial commit