[EPIC] Remove the NodeJS server used in frontend

[madsnedergaard]

Description

The server complicates the build and local development, while impacting performance and SEO. It mainly exists because of localisation, which should/could be improved and replaced on client-side anyway :)

See further discussions here: https://github.com/electricitymap/electricitymap-contrib/issues/3262

I've started the work here, but realised there's several areas needed to be addressed here. See list below.

Tasks in this

• [x] Replace clientVersion usage: #3838
• [x] Replace localisation approach (no more inlining all translations in HTML) TODO: Split into smaller PRs
  • Move translation files #3840
  • Change zone-name #3839
  • Prepare mobileapp for i18next backend #3841
  • Add new setup in parallel with old server-based setup #3842
  • Switch to using new setup in app #3843
  • Remove localisation from server (and generate-index script) #3848
  • Move translation-status functionality to a local-only setup (also done in #3848)
  • Cleanup (if needed, hard to tell before all the other PRs are merged)
• Create static index.html during build step
• Ensure all redirects (including Facebook redirects) still work
• Deploy everything to a bucket with another subdomain, transfer when it all works!

[VIKTORVAV99]

Not sure if this is helpful or not but the HtmlWebpackPlugin can (and should) be used for generating the index.html, it also supports ejs templates so we can mostly use the current template without huge changes, it's just the facebook specific stuff that will need to have a solution.

We should also change how we handle the page title as it currently using the index.ejs to be generated, we should switch this to a static electricityMap title and then update it using client side JS. (this can be done already if we want)

[madsnedergaard]

Let's try replacing this issue with a Project: https://github.com/orgs/electricitymap/projects/29/ :)