Enhance API documentation and restructure routes for improved clarity

- Updated README.md to include comprehensive Swagger documentation details, highlighting new features and endpoint categories.
- Introduced a new router structure to streamline route registration for admin and public endpoints, enhancing maintainability.
- Updated health check endpoint documentation to reflect comprehensive server status information.
- Enhanced customer and company management routes with improved descriptions and examples in Swagger.
- Refactored customer and user handlers to remove obsolete route registrations, aligning with the new router structure.
- Improved response handling in customer and user services to utilize string IDs consistently.
- Updated validation rules and forms for customer management to support multiple company assignments.
- Enhanced logging practices across services to ensure better traceability and error handling.

README.md

@@ -47,6 +47,78 @@ This system implements **Clean Architecture** with:
 - **Time Handling**: Unix timestamps throughout the application
 - **API Documentation**: Auto-generated Swagger documentation
 
+## 📋 API Documentation
+
+### Swagger/OpenAPI 3.0 Documentation
+
+The Tender Management API features comprehensive, auto-generated Swagger documentation with:
+
+#### 🚀 **Version 2.0.0 Features**
+- **Comprehensive API Coverage**: All endpoints documented with detailed descriptions, examples, and error responses
+- **Interactive API Testing**: Built-in Swagger UI for testing endpoints directly from the documentation
+- **Authentication Integration**: Bearer token authentication examples and testing capability
+- **Request/Response Examples**: Real-world examples for all data structures and API calls
+- **Error Documentation**: Detailed error codes, messages, and troubleshooting information
+
+#### 📊 **API Endpoints Categories**
+- **Health**: System monitoring and health check endpoints
+- **Authorization**: User authentication, token management, and session handling
+- **Users**: Administrative user management with RBAC (Role-Based Access Control)
+- **Customers-Admin**: Web panel customer management with advanced filtering
+- **Customers-Authorization**: Mobile app customer authentication and profile access
+- **Companies-Admin**: Comprehensive company management with search, filtering, and analytics
+- **Companies-Mobile**: Mobile-optimized company lookup and information retrieval
+
+#### 🔧 **Documentation Access**
+- **Local Development**: `http://localhost:8081/swagger/`
+- **Interactive Testing**: All endpoints can be tested directly from the Swagger UI
+- **Authentication**: Use the "Authorize" button to set Bearer tokens for protected endpoints
+- **Export Options**: JSON and YAML formats available for API specifications
+
+#### 📝 **Enhanced Features**
+- **Detailed Descriptions**: Each endpoint includes comprehensive business logic explanations
+- **Parameter Validation**: Complete validation rules and constraints for all input parameters
+- **Response Examples**: Real-world response examples with proper HTTP status codes
+- **Security Schemes**: JWT Bearer token authentication clearly documented
+- **Error Handling**: Comprehensive error response documentation with troubleshooting guides
+- **Filtering & Pagination**: Advanced query parameters for list endpoints with examples
+- **Business Logic**: Context-aware descriptions explaining when and how to use each endpoint
+
+#### 🏗️ **Technical Specifications**
+- **OpenAPI/Swagger 2.0**: Industry-standard API documentation format
+- **Auto-Generation**: Documentation automatically updated from code annotations
+- **Type Safety**: Strong typing with Go struct validation and examples
+- **Validation Rules**: Complete govalidator integration for request validation
+- **Consistent Response Format**: Standardized API response structure with metadata
+
+#### 💡 **Usage Examples**
+```bash
+# Access Swagger UI
+curl http://localhost:8081/swagger/
+
+# Download API specification
+curl http://localhost:8081/swagger/doc.json
+
+# Test authentication endpoint
+curl -X POST "http://localhost:8081/admin/v1/login" \
+  -H "Content-Type: application/json" \
+  -d '{"username": "admin", "password": "password"}'
+```
+
+#### 🔐 **Authentication Testing**
+1. Navigate to Swagger UI at `/swagger/`
+2. Click "Authorize" button
+3. Enter: `Bearer <your_jwt_token>`
+4. Test protected endpoints directly from the interface
+
+### API Design Principles
+- **RESTful Design**: Consistent REST principles with proper HTTP methods and status codes
+- **Clean Architecture**: Domain-driven design with clear separation of concerns
+- **Validation**: Comprehensive input validation with meaningful error messages
+- **Security**: JWT-based authentication with proper token management
+- **Performance**: Optimized queries with pagination and filtering capabilities
+- **Maintainability**: Auto-generated documentation stays in sync with code changes
+
 ## 🔧 Development
 
 ### Prerequisites