add comprehensive test suite with 47 tests

unit tests:
- formatSearchResults edge cases
- performChatCompletion success and error paths
- performSearch parameter handling
- API response validation
- timeout and error handling
- concurrent requests
- special characters and long content

integration tests:
- all four tool types (ask, research, reason, search)
- real-world scenarios
- multi-turn conversations
- performance and reliability

tests run against actual implementation via imports
vitest configured with proper env vars and exclusions

Author: 27Bslash6