- Added comprehensive test suite for MessageTool (message_test.go)
- 10 test cases covering all acceptance criteria:
- Success returns SilentResult with proper ForLLM status
- ForUser is empty (user receives message directly)
- Failure returns ErrorResult with IsError=true
- Custom channel/chat_id parameter handling
- Error scenarios (missing content, no target, not configured)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
