Added Skill (for Agentic tools) for store-backend - #2563

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: docker/build-push-action@ca877d9245402d1537745e0e356eab47c3520991, docker/setup-buildx-action@f7ce87c1d6bead3e36075b2ce75da1f6cc28aaca. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/