chore(deps-dev): bump jsdom to 30, @types/node, globals, svelte-check

Consolidates dependabot PRs #236, #237, #238 and #239:

  jsdom          29.1.1 -> 30.0.0
  @types/node    26.1.1 -> 26.1.2
  globals        17.7.0 -> 17.8.0
  svelte-check    4.7.3 -> 4.7.4

jsdom 30 is a major bump that drops Node 20; it is landed together with the
Node 26 runner bump because neither is green without the other.

Author: kellenmurphy