fix: 修复 OSS_ENDPOINT 拼写错误 aliiyuncs → aliyun

OSS_ENDPOINT 默认值中的域名拼写错误：
- 错误：oss-cn-hangzhou.aliiyuncs.com（多了一个 i）
- 正确：oss-cn-hangzhou.aliyuncs.com

同步修复：
- apps/api/app/config.py
- packages/shared/config.py
- tests/unit/test_config_oss.py

apps/api/app/config.py

@@ -80,7 +80,7 @@ class Settings(BaseSettings):
     CELERY_RESULT_BACKEND: str = "redis://localhost:6379/1"
 
     # OSS 七牛云相关
-    OSS_ENDPOINT: str = "oss-cn-hangzhou.aliiyuncs.com"
+    OSS_ENDPOINT: str = "oss-cn-hangzhou.aliyuncs.com"
     OSS_ACCESS_KEY_ID: str = ""
     OSS_ACCESS_KEY_SECRET: str = ""
     OSS_BUCKET_NAME: str = "xiaoxia-autocut"