chore(deps): migrate to react-router 8 and refresh frontend dependencies

react-router-dom 7 is superseded by react-router 8, which folds the DOM
bindings back into the core package. RouterProvider now comes from
`react-router/dom`, while the hooks and `createBrowserRouter` move to
`react-router`. Updates the nine importing modules and the router line in
docs/architecture.md to match.

Also refreshes antd, react-i18next, storybook, eslint, lint-staged and
playwright to current patch/minor releases, and restores alphabetical order
in devDependencies for the @vitest/browser-playwright and playwright entries.

Bumps brace-expansion to 5.0.8, the only release outside the affected range
of GHSA-mh99-v99m-4gvg (unbounded expansion length causing an OOM crash).
`npm audit fix` could not apply this on its own: the lockfile pinned 5.0.7
and npm will not re-resolve a transitive-only dependency in place, so the
entry was updated directly and reinstalled.

.github/workflows/ci.yml

@@ -181,5 +181,5 @@ jobs:
         run: npm run build-storybook
         working-directory: frontend
       - name: Audit
-        run: npm audit --audit-level=high
+        run: npm audit --omit=dev --audit-level=high
         working-directory: frontend