Issue #21: API Testing and Mocking

[Vivaanfbcmc]

Description

Create comprehensive API testing with proper mocking for external services.

Requirements

• Set up API mocking with MSW (Mock Service Worker)
• Create mock data for all external APIs
• Implement API response testing
• Add error scenario testing
• Create API performance testing
• Add API contract testing

Acceptance Criteria

• All API endpoints are mocked
• Error scenarios are properly tested
• API performance is monitored
• Contract testing ensures API compatibility
• Tests run without external dependencies

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