✅ Add test suite for Billy's code review logic

[chitcommit]

Testing Task

Add comprehensive test suite for Billy Bullshit.

Coverage Needed:

1. Unit Tests

   • BillyAgent class methods
   • Code review logic
   • BS detection patterns
   • Rating algorithm

2. Integration Tests

   • API endpoints
   • Conversation storage
   • AI model fallbacks

3. E2E Tests

   • Full code review flow
   • Multi-turn conversations
   • Error handling

Test Frameworks:

• Vitest for unit/integration tests
• Playwright or Puppeteer for E2E

Acceptance Criteria:

• >80% code coverage
• All endpoints tested
• BS detection examples validated
• CI/CD pipeline integrated

Priority: High