feat: LLM/Embedding 重试次数纳入 system.yaml 统一配置

- system.yaml: llm.max_retries(死配置) 改为 llm.max_attempts；embedding 段新增 max_attempts
- llm/client.py: LLMConfig 新增 max_attempts（默认 3 兜底），load_llm_config 读取配置
- llm/extractor.py: translate_and_extract(_async) max_attempts=None 时取 config.max_attempts
- embedding/client.py: load_embedding_config 读取 embedding.max_attempts
- scheduler/reporter.py: _call_llm_simple max_retries=None 时取 max_attempts-1
- 新增 2 个配置读取测试；已同步 pi5 验证

llm/extractor.py

@@ -226,7 +226,7 @@ def translate_and_extract(
     article: ProcessedArticle,
     *,
     template: PromptTemplate | None = None,
-    max_attempts: int = DEFAULT_MAX_ATTEMPTS,
+    max_attempts: int | None = None,
 ) -> EnTranslatedArticle:
     """同步翻译 + 事件抽取（单篇文章，带重试）。
 
@@ -235,7 +235,8 @@ def translate_and_extract(
         config: LLM 配置
         article: 待处理的英文新闻
         template: Prompt 模板，默认加载 prompts/translation_and_extraction.md
-        max_attempts: 最大重试次数
+        max_attempts: 最大尝试次数（含首次）；None 时取 config.max_attempts
+            （来自 system.yaml llm.max_attempts）
 
     Returns:
         EnTranslatedArticle 含双语内容 + 事件
@@ -243,6 +244,8 @@ def translate_and_extract(
     Raises:
         LLMCallError: 所有重试均失败
     """
+    if max_attempts is None:
+        max_attempts = config.max_attempts
     tpl = template or PromptTemplate()
     system_prompt, user_prompt = tpl.render(article)
 
@@ -305,10 +308,12 @@ async def translate_and_extract_async(
     article: ProcessedArticle,
     *,
     template: PromptTemplate | None = None,
-    max_attempts: int = DEFAULT_MAX_ATTEMPTS,
+    max_attempts: int | None = None,
     semaphore: asyncio.Semaphore | None = None,
 ) -> EnTranslatedArticle:
     """异步翻译 + 事件抽取（批处理用），与同步版逻辑等价。"""
+    if max_attempts is None:
+        max_attempts = config.max_attempts
     tpl = template or PromptTemplate()
     system_prompt, user_prompt = tpl.render(article)