Update docs site branding

[sarina]

• Site logos
• Favicon
• Re-theme persona images

• Folder with new logos
• Logo uses Primary Navy #092B4D and Brand Magenta #9D0054
• New Brand Guidelines with colour palette included (these colours are pulled from OeX Paragon) - Open edX Brand Guidelines 2026.pdf

[sarina]

Deadline - Verawood cut

[sarina]

Logos are a pain but favicon is easy, https://github.com/openedx/docs.openedx.org/blob/main/source/conf.py#L219-L220

logos are local to each repo because I believe the version of sphinx we were on didn't let you put in a URL for the logo, the new version might and so it might be worth checking that. Ideally we replace all the local static logos with a url to the logos.openedx.org url for the new logo.

[sarina]

• @feanil will change the favicon
• persona PR docs: Update Icons for new Branding color (magenta) #1408