docs: Update home page and server/client index pages to highlight the most important information

[afolson]

Depends on #196 getting merged.

The home page is more marketing-focused and should be more focused on documentation now that we have more of it. Create paths for people to follow depending on what they're trying to do:

• Introduction to explain SwimOS at a high level
• CTA to get started for free in several locations
• Developers should be driven towards Rust/Java dev guides and tutorials but also made aware that reference docs exist.
• Developers trying to build front ends for apps should go to Typescript docs
• Users just looking for more info should be able to find demos and concept docs

@will347 Would love your thoughts on this. I'm thinking we show those three options and then scroll down to some anchor with a list of relevant documentation. This would keep the happy path choices above the fold and keeps that content skimmable for folks who don't know what they want yet. I'm totally open to ideas though!