refactor: 修复 quality_check 字段命名不一致

l2_Subsection_quality -> l2_subsection_quality

core/construction_review/component/minimal_pipeline/simple_processor.py

@@ -519,7 +519,7 @@ class SimpleDocumentProcessor:
             )
 
         # 二级小节质量
-        quality_result["l2_Subsection_quality"] = {
+        quality_result["l2_subsection_quality"] = {
             "extracted_count": l2_count,
             "expected_count": default_total_subsections,
             "extraction_rate": round(l2_rate * 100, 2),