fix: resolve YAML config path relative to project root

Ensure config/settings.yaml can be found when running from any working
directory by resolving the path relative to the settings.py file location
rather than the current working directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/settings.py

@@ -45,7 +45,12 @@ class Settings(BaseModel):
 
 def load_settings(config_path: str = "config/settings.yaml") -> Settings:
     """加载 YAML 配置文件"""
+    # Resolve relative to the project root (where config/ directory exists)
     path = Path(config_path)
+    if not path.is_absolute():
+        # __file__ is config/settings.py, so parent.parent gives us project root
+        project_root = Path(__file__).resolve().parent.parent
+        path = project_root / config_path
     if not path.exists():
         raise FileNotFoundError(
             f"配置文件不存在: {config_path}\n"