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

tests/test_llm.py

@@ -457,6 +457,12 @@ class TestLoadLLMConfig:
         with pytest.raises(ValueError, match="API key 未配置"):
             load_llm_config(provider="deepseek")
 
+    def test_max_attempts_from_system_yaml(self, monkeypatch):
+        """重试次数取自 system.yaml llm.max_attempts（当前 3）。"""
+        monkeypatch.setenv("DEEPSEEK_API_KEY", "sk-deepseek-test-key")
+        config = load_llm_config(provider="deepseek")
+        assert config.max_attempts == 3
+
 
 # --------------------------------------------------------------------------- #
 # translate_and_extract（mock LLM）