feat: compose a subgraph from its sdl - #96

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Total Tests: 154 Suites 📂: 1 Passed ✅: 154 Failed ❌: 0 Canceled 🚫: 0 Skipped ⏭️: 0 Todo 📝: 0 Duration 🕐: 6179.460ms