Enhance stream check service with configurable test models:
- Add claude_model, codex_model, gemini_model to StreamCheckConfig
- Support reasoning effort syntax (model@level or model#level)
- Parse and apply reasoning_effort for OpenAI-compatible models
- Remove hardcoded model names from check functions
- Add unit tests for model parsing logic
- Remove obsolete model_test source files
This allows users to customize which models are used for health checks.
Add new stream-based health check module to replace model_test:
- Add stream_check command layer with single and batch provider checks
- Add stream_check DAO layer for config and log persistence
- Add stream_check service layer with retry mechanism and health status evaluation
- Add frontend HealthStatusIndicator component
- Add frontend useStreamCheck hook
This provides more comprehensive health checking capabilities.