Dev: Add Design System and Style Guidelines section

[marcuspollio]

• See FPA grant 58: Design System and Style Guidelines

Open questions:

• Everything in /dev/design?
• Linear/flat or nested pages structure?
• One page per component or multiple components in a single page?
• Shortcodes for components are probably the most flexible implementation for the website, but it can become quite complex. Maybe simple SVG files with chroma support (light/dark vars) are sufficient? I would not go the data file route, as it is probably overkill and too much to maintain, even though powerful.
• How much "interaction" do we want? Probably very little or none. Tiny JS or CSS in SVG can be added for enhancement if wanted.
• How should it be exposed in the CMS? Minimal with focus on text content, or full editable components too (probably too much)?
• TBD

[marcuspollio]

FYI @kadet1090