Migrate to Svelte 5

[ai]

Svelte 5 looks pretty stable.

New version allows us to use more precise types in components and avoid unnecessary <div> in slots. Also it works better with nested CSS.

[github-actions[bot]]

Pull request auto-reviewer

• Don’t rush. Check all changes in PR again.

• Run pnpm test.

• Think about changing documentation.

  • If you added a script to scripts/, add a comment with a description.
  • If you added a new folder, add its description to the project’s README.md.
  • If you added config, describe how we use this tool in the config’s comment.
  • Try to focus on “why?”, not “how?”.

• Think about code testing.

• If you added a new dependency, check our requirements.

• Think about moving code to core/. What code will also be useful on other platforms?

• Think about HTML semantics.

• Think about accessibility. Try to search for a11y recommendations for your case. Think about how screen reader users will use the tool. Is it easy to use on a screen with bad contrast?

• The UI was checked in Chrome and Firefox (and Safari or Epiphany if you have them).

• Since you’ve made changes to files in web/main/ consider these points:

  1. Do you need to backport styles changes to web/public/404.html or web/public/500.html?
  2. Think about app loading styles inlined in index.html.