Refresh frontend tooling devDependencies and drop dead packages

Dev-only updates to resources/ext.neowiki. Runtime libs (vue, codex,
pinia) stay pinned to the versions MediaWiki 1.43 provides at runtime.

- Align with eslint-config-wikimedia 0.32.4: @stylistic/eslint-plugin
  ^2.8.0 -> ^3.1.0 and eslint-plugin-unicorn ^55 -> ^56.0.1 (both still
  support eslint 8, which the wikimedia config pins us to).
- types-mediawiki ^1.8.0 -> ^2.0.0 (the v2 removed aliases are unused).
- jsdom ^25 -> ^29.1.1 (+ @types/jsdom ^28). Its stricter, more
  spec-compliant selector engine required replacing fragile
  `div > div > :is(a, span)` selectors in RelationDisplay.spec.ts that
  relied on the query scope element itself matching the first `div`.
- @types/node ^22 -> ^24 to match the Node 24 CI/runtime.
- axios -> ^1.18.1, less -> ^4.6.7 (in-range refresh).
- Replace the unmaintained npm-run-all with its drop-in fork
  npm-run-all2 ^8.0.4.
- Declare stylelint directly (previously only transitive via the config).
- Remove dead devDependencies: @types/dompurify (no dompurify dep or
  usage) and sass-embedded (no SCSS in the project).

Pin @vue/test-utils to 2.4.6: 2.4.11's attachTo path calls Vue 3.5's
app.onUnmount, which throws against our pinned Vue 3.4.27.

vite/vitest are upgraded in a separate commit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: alistair3149