🌐 Feature: Add Swagger / OpenAPI Documentation

[yogeshsanodiya59-web]

Description
The project currently lacks interactive API documentation, making it difficult for developers to understand and test available endpoints.

Proposed Solution
Integrate SpringDoc OpenAPI to automatically generate API documentation and provide an interactive Swagger UI.

Tasks

• Add SpringDoc OpenAPI dependency
• Configure OpenAPI metadata (title, version, description)
• Enable Swagger UI endpoint
• Verify API docs available at /swagger-ui.html or /swagger-ui/index.html
• Add annotations (@Operation, @Tag, etc.) for better documentation
• Test all endpoints via Swagger UI

Expected Outcome

• Interactive API documentation UI
• Easy endpoint testing without external tools
• Improved developer experience and API clarity

Additional Context
Swagger/OpenAPI is a standard for REST API documentation and will make the project more accessible for contributors and users.