feat: Add base project structure with API and web components

api/app/core/upload_enums.py

@@ -0,0 +1,10 @@
+from enum import Enum
+
+
+class UploadContext(str, Enum):
+    """上传上下文枚举，定义文件上传的目的和分类"""
+    AVATAR = "avatar"
+    APP_ICON = "app_icon"
+    KNOWLEDGE_BASE = "knowledge_base"
+    TEMP = "temp"
+    ATTACHMENT = "attachment"