Add comprehensive testing infrastructure (unit, integration, E2E)

[benmed00]

Problem

Lack of comprehensive test coverage for critical utilities and API routes makes it difficult to ensure code quality and prevent regressions.

Expected Solution

Add comprehensive testing:

• Unit tests for password policy, 2FA, export utilities
• Integration tests for API routes (search, export)
• E2E tests for critical user flows (auth, search, export)

Related

This issue is resolved by PR #75.