test: 修复端到端管道运行器和 Layer B IndexError - Closes #14

- run_pipeline.py: 修复 subprocess env 传递、parsed_path 检测、Unicode 编码
- test_main_health.py: 修复 _is_functional_section 空章节名 IndexError
- 端到端测试管道: doc_parser → ir_generation(4 steps) → acceptance tests
- 测试发现问题汇总至 dev issue #15

tests/acceptance/test_main_health.py

@@ -95,6 +95,8 @@ def _is_functional_section(section_name: str) -> bool:
             return False
     # Documents with only a title (no section number) — check for functional keywords
     sec_num = _section_number(section_name)
+    if not sec_num:
+        return False
     if "." not in sec_num and not sec_num[0].isdigit():
         func_keywords = ["策略", "规则", "功能", "限制", "流程", "配置", "场景",
                          "约束", "条件", "方案", "逻辑", "处理", "机制", "禁止"]