Add login endpoint

[javidahmed64592]

This pull request introduces a new authenticated /login API endpoint, updates documentation to reflect the new endpoint and API documentation features, and improves security configuration for content security policies. Comprehensive tests are added for the new endpoint and model, ensuring robust coverage.

API Enhancements

• Added a new authenticated GET /api/login endpoint that verifies API tokens and returns a standardized login success response using the new GetLoginResponse model. [1] [2] [3]
• Updated the OpenAPI documentation and all relevant markdown files (README.md, API.md, DOCKER_DEPLOYMENT.md, SMG.md) to document the new /login endpoint, its usage, and the availability of Swagger UI and ReDoc for interactive API documentation. [1] [2] [3] [4] [5]

Security Improvements

• Enhanced the content_security_policy in config.json to allow necessary scripts, styles, and images for API documentation UIs (Swagger UI, ReDoc) while maintaining secure defaults.

Testing and Code Quality

• Added unit and integration tests for the new GetLoginResponse model and /login endpoint, ensuring correct behavior and coverage. This includes updates to test files and test class naming for clarity. [1] [2] [3] [4] [5] [6]
• Minor improvements to test timestamp handling for consistency in assertions. [1] [2]