<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **New Features**
* Added an npm build script to simplify project compilation.
* **Chores**
* Simplified CI dependency installation to use standard npm install.
* Added a new deployment test job that runs multi-service integration
checks, build, health checks, and graceful shutdown.
* Introduced an environment-variable gate to allow opting into local
filesystem behavior in production.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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