feat: user install guide

[1-leo]

The goal is to have an install guide that is easy to understand.
RN it's in apps/[appid]/install

User Story:
As a user, I want an easy to follow guide so I don't get stuck when trying to install an app.

As a developer, I want to be able to send resources to my users that make it easy for them to install my application.

Limitations:

• deeplink setup (open install page if zapstore not installed)
• replace google image
• insert video (player) if wanted
• duplicated code in install/+page.js, install/+page.server.js [not sure how this works in sveltekit]
• adjust fonts and zapstore ci
• the app color is extracted from the logo, could be dev specified.

Motivation:
I am not sure if this is a wanted feature for zapstore, thats why this pr lacks polishing, just want to get it out there to discuss and continue to work.

[NielLiesmons]

We are looking into how to skip several of these steps by allowing you to send a link to people of on-demand Zapstore APKs that have the app(s) you define preconfigured in there.

[NielLiesmons]

This is still very useful nevertheless.
I like this app-logo color thing you did.

[NielLiesmons]

I'm checking how to best incorporate...

[1-leo]

We are looking into how to skip several of these steps by allowing you to send a link to people of on-demand Zapstore APKs that have the app(s) you define preconfigured in there.

That would be awesome!!! However, the first part would still be useful.
The page could be made configurable with query params like zapstore.dev/install?appid=com.minibits_wallet

[NielLiesmons]

Yes, exactly!

[NielLiesmons]

I've been meaning to add an Install CTA on web (again) #31 and this might be. the way forward for that tbh.