Implement Visual Abstract as vector graphic (SVG)

[bootsa]

Take @maudbv's visual abstract design from Miro, export as PDF, convert to SVG & clean up.

Miro doesn't export as a true vector graphic format but does allow to export as a vector graphic embedded in an SVG.

The image will need styling for light & dark modes (as with other vector graphics on the site - e.g. te patner logos on the main page).

• Use a tool to extract the vector image from the pdf and save as SVG. This can be done using Inkscape but requires significant clean-up.

Related to:

• Add Light/Dark/Follow-OS mode switch #3

[bootsa]

Further enhancement could include:

• revealing parts of the diagram governed by the scroll position (scrolly-telling).
• altering the layout so the abstract expands outside of standard text column width on wider screens.