feat: add MCP tools registration to LLM service

- Add RegisterTools method to ILLMService interface
- Create shared MCP to eino tool converter
- Auto-register built-in uixt tools in XTDriver initialization
- Refactor MCPHost to use shared converter
- Add comprehensive test coverage for tool conversion

This enables doubao-1.5-thinking-vision-pro model to access
MCP tools through function calling mechanism.

tests/step_ui_test.go

@@ -101,7 +101,7 @@ func TestStartToGoal(t *testing.T) {
 `
 
 	testCase := &hrp.TestCase{
-		Config: hrp.NewConfig("run ui action with start to goal").
+		Config: hrp.NewConfig("连连看小游戏自动化测试").
 			SetLLMService(option.DOUBAO_1_5_THINKING_VISION_PRO_250428),
 		TestSteps: []hrp.IStep{
 			hrp.NewStep("启动抖音「连了又连」小游戏").