feat(website): Improve rebranding theming & home

[yanthomasdev]

Summary

This PR continues the changes made to move into the v2 website, namely:

• Fixed some issues on the homepage (card content not accessible for translators, missing sponsors, horizontal scrollbar, etc.)
• Changed the light theme colors to the closest possible with enough contrast.
• Added some missing assets for the website: new avatar logo for team/core blog post author, og image, favicon. (Keep the old logo used in blog posts for historical reasons).

Test Plan

• I've run a few a11y tests in pages to ensure no color contrast issues continued
• Visually tested components and all blog pages + playground for any missing assets

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[ematipico]

I checked and everything is fine now. The contrast issues are gone! Thank you @Yan-Thomas for these massive improvements!