refactor(structure): reorganize app layout

BREAKING CHANGE: root backend/frontend directories and old run/manage entrypoints were removed. Use apps/backend, apps/frontend, and python main.py commands instead.

apps/backend/schemas/response.py

@@ -0,0 +1,28 @@
+"""
+统一的 API 响应 Schema
+"""
+from typing import Generic, TypeVar, Optional
+from pydantic import BaseModel
+
+
+T = TypeVar('T')
+
+
+class ApiResponse(BaseModel, Generic[T]):
+    """统一成功响应"""
+    success: bool = True
+    data: Optional[T] = None
+    message: Optional[str] = None
+
+
+class ErrorDetail(BaseModel):
+    """错误详情"""
+    code: str
+    message: str
+    field: Optional[str] = None  # 字段验证错误时使用
+
+
+class ErrorResponse(BaseModel):
+    """统一错误响应"""
+    success: bool = False
+    error: ErrorDetail