Apply the Data Privacy Stack community brand to the documentation site
ahead of the project transition.
- mkdocs.yml: rename site to "Presidio", add light/dark palette toggle,
Inky icon as logo + favicon, brand fonts, and UX features
- stylesheets/extra.css: full violet/indigo theme (light + dark), hero
wordmark lockup, and component polish
- index.md: add hero block (mascot + "Presidio" / "by data privacy stack")
- api-docs: replace Microsoft logo with the Inky mascot and recolor the
ReDoc theme to match the new palette
- assets: add Inky mascot, favicon, and app-icon SVGs
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
