Add wiki: theme palettes, colour roles, customizing and contributing Six pages covering both theme families. Every hex value is read from the committed .vstheme files rather than restated by hand. Build and release steps are linked rather than repeated, so they cannot drift from README.md and .github/RELEASING.md. Removes the Bootstrap placeholder page, which existed only to provision this repository. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>