refactor(opencode): use existing mem0 SDK instead of delegating to MCP, load skills properly instead of dumping them in .opencode - #5323

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