feat(notifications): optional single summary notification + launcher badge - #1335

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-java@v4, gradle/actions/setup-gradle@417ae3ccd767c252f5661f1ace9f835f9654f2b5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to restore v9-gradle|Linux|test[49c05c747b8c84ad960fd841f8221d5e]-5ea5f9144ff8308a4746b7f1ba2c32fdcd050793: Error: Cache service responded with 400

setup-java v4 is deprecated and will no longer receive updates. Please migrate to actions/setup-java@v5.