Add tests for 100% code coverage

Added tests for two uncovered scenarios in chatController.ts:
- Line 154: Handles popup blocking when window.open returns null
- Line 164: Ignores postMessage events from sources other than the opened popup window

These tests improve the security and robustness of the chat controller by ensuring:
1. The controller gracefully handles popup blockers without throwing errors
2. PostMessage communication is validated to only accept messages from the intended popup window

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Add test coverage for chatController and businessHours branches

- Add test for line 175 else branch in chatController.ts (when popup is NOT closed)
- Add test for when nextState is undefined (not in business hours)
- Add test for state reuse when hours haven't changed (object reference stability)

These tests address the coverage gaps identified in code review.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: 2 people