add CI/CD workflows and improve project documentation

[NRG-Wardog]

Summary

Professionalize the repository’s engineering workflow and documentation.

Changes

• Added CI for pull requests and pushes to main/ci

  • C++ build and unit tests
  • Express API tests
  • React web production build
  • Mobile dependency validation

• Added release workflow for semantic version tags and manual runs

  • Builds the C++ service and web client
  • Uploads a versioned release artifact

• Reworked the README with:

  • Architecture overview
  • Setup and configuration
  • Development commands
  • Testing and CI/CD documentation
  • Release process
  • Troubleshooting
  • Repository structure
  • Contribution, security, and licensing guidance

Validation

• Web API tests passed
• React client build passed
• Mobile dependencies installed successfully
• Git diff checks passed
• C++ validation is configured in CI; it could not be run locally because CMake is unavailable on the development host