Fix API path alignment between frontend tests and implementation

[kenahrens]

Summary

• Resolves CI/CD test failures by aligning frontend API paths with test expectations
• Updates frontend to use simplified API paths (/api/transactions vs /api/transactions-service)
• Adds new simplified routes to API Gateway while maintaining backward compatibility
• All frontend tests now pass successfully

Key Changes

• Frontend API clients: Updated to use simplified paths matching test expectations
• API Gateway routing: Added simplified routes (/api/users/**, /api/accounts/**, /api/transactions/**)
• Account transactions: Added specific routing for /api/accounts/{id}/transactions patterns
• Backward compatibility: Maintains original service-specific paths for existing integrations

Test Results

• ✅ All frontend unit tests now pass (103/103)
• ✅ API path mismatch issues resolved
• ⚠️ Coverage threshold warnings (expected - not all code paths tested)

Routes Added

# New simplified routes
/api/users/** → /user/**
/api/accounts/** → /accounts/**
/api/transactions/** → /transactions/**
/api/accounts/{id}/transactions → /accounts/account/{id}/transactions

# Legacy routes maintained
/api/user-service/** → /user/**
/api/accounts-service/** → /accounts/**
/api/transactions-service/** → /transactions/**

🤖 Generated with Claude Code