chore(deps): ignore jsdom majors until the Node 22 migration

jsdom 30.x requires Node ^22.22.2 || ^24.15.0 || >=26 while CI and Docker are
on Node 20. On Node 20 the incompatibility surfaces indirectly as vitest
failing to start its pool workers rather than as a clean engine error, so #877
reads like a flaky frontend failure. Same wall as @testing-library/jest-dom 7.

.github/dependabot.yml

@@ -47,10 +47,14 @@ updates:
       # revisit each as a dedicated migration, not a dependency bump.
       #   @vitejs/plugin-react 6.x peers vite@^8 (we are on vite 6.x).
       #   @testing-library/jest-dom 7.x requires Node >=22 (CI/Docker use 20).
+      #   jsdom 30.x requires Node ^22.22.2 || ^24.15.0 || >=26 (same wall);
+      #     on Node 20 it surfaces as vitest failing to start its pool workers.
       - dependency-name: "@vitejs/plugin-react"
         update-types: ["version-update:semver-major"]
       - dependency-name: "@testing-library/jest-dom"
         update-types: ["version-update:semver-major"]
+      - dependency-name: "jsdom"
+        update-types: ["version-update:semver-major"]
 
   # GitHub Actions workflow pins.
   - package-ecosystem: "github-actions"