fix: Address Shorebird SEO issues

[eseidel]

Google keeps emailing me that we have SEO issues:
https://search.google.com/search-console/index

[eseidel]

[eseidel]

I looked briefly today. Some of the noindex seem to be just generated re-directs from astro. (e.g. privacy.html). Some aren't though? (like guides/code-push/quick-start).

Overall things seem "fine" and not blocked on this part of SEO. I think we mostly need more content.

[eseidel]

shorebirdtech/shorebird#1626 isn't directly related but is in the same vein of "stuff we need to do for our non-code infrastructure that someone just needs to spend half a day doing". This one is for improving our website SEO, the linked bug is about fixing our MX record setup to have the modern configuration bits.

[eseidel]

Our favicon looks bad. Not sure why. It's an SVG in a 1:1 ratio I believe like Google recommends:
https://developers.google.com/search/docs/appearance/favicon-in-search

[eseidel]

Probably our icon is just too complicated and needs to be simplified for display in such scenarios.