[Web Vitals] 100 lighthouse score

[kptdobe]

Goal is to make the required changes to hit a 100 to the lighthouse score. This includes:

• revisit the loading sequence of the post page
• revisit the loading sequence of the homepage page
• revisit the loading sequence of the author page
• revisit the loading sequence of the topic page
• setup server pushes (resources to push to be defined)

This requires #662

[rofe]

While it would definitely be great to reach 100 on all page types, I think we can also narrow focus to the homepage and the post page. Author and topic pages get very little traffic and are almost never linked anywhere.