fix(ai): 修复 OpenAI 结构化输出解析问题并重构代码结构

- 修复 OpenAI structured output 的 properties 包装层解析问题
- 重构 parseCustomSchemaResult 函数，提高代码可维护性：
  - 拆分为多个职责单一的小函数
  - 消除重复的字段提取逻辑
  - 采用清晰的策略模式处理不同解析场景
- 增强测试用例，添加具体的数值和结构验证
- 保持完全向后兼容，所有现有测试通过

Fixes: TestQueryFunctionality/ComprehensiveAnalysis 测试失败问题

uixt/ai/querier_test.go

@@ -183,6 +183,9 @@ func TestQueryFunctionality(t *testing.T) {
 		assert.NotNil(t, gameInfo)
 		assert.NotEmpty(t, gameInfo.Content)
 		assert.NotEmpty(t, gameInfo.Thought)
+		assert.Equal(t, 4, gameInfo.Rows)
+		assert.Equal(t, 3, gameInfo.Cols)
+		assert.Equal(t, 5, gameInfo.TotalIcons)
 
 		t.Logf("Custom Schema Query Result: %+v", gameInfo)
 	})
@@ -206,6 +209,16 @@ func TestQueryFunctionality(t *testing.T) {
 		assert.NotEmpty(t, result.Thought)
 		assert.NotNil(t, result.Data)
 
+		gameAnalysisResult, ok := result.Data.(*GameAnalysisResult)
+		assert.True(t, ok)
+		assert.NotNil(t, gameAnalysisResult)
+		assert.NotEmpty(t, gameAnalysisResult.Content)
+		assert.NotEmpty(t, gameAnalysisResult.Thought)
+		assert.NotEmpty(t, gameAnalysisResult.GameType)
+		assert.Equal(t, 4, gameAnalysisResult.Dimensions.Rows)
+		assert.Equal(t, 3, gameAnalysisResult.Dimensions.Cols)
+		assert.Equal(t, 12, len(gameAnalysisResult.Elements))
+
 		t.Logf("Comprehensive Analysis Result: %+v", result.Data)
 	})
 }