chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/account/schemas.py

@@ -0,0 +1,53 @@
+from typing import List
+from ninja import Schema, ModelSchema
+from pydantic import EmailStr, Field
+
+from .models import User, RoleChoices
+
+
+class UserListSchema(ModelSchema):
+    @classmethod
+    def get(cls, obj):
+        raw_password = obj.raw_password if obj.role != RoleChoices.SUPER else ""
+        return cls(
+            id=obj.id,
+            username=obj.username,
+            raw_password=raw_password,
+            role=obj.role,
+            date_joined=obj.date_joined,
+            last_login=obj.last_login,
+            is_active=obj.is_active,
+        )
+
+    class Meta:
+        model = User
+        fields = [
+            "id",
+            "username",
+            "raw_password",
+            "role",
+            "date_joined",
+            "last_login",
+            "is_active",
+        ]
+
+
+class UserRegistrationSchema(Schema):
+    username: str
+    email: EmailStr
+    password: str = Field(min_length=6, max_length=20)
+
+
+class UserLoginSchema(Schema):
+    username: str
+    password: str
+
+
+class BatchUsersIn(Schema):
+    names: List[str]
+    classname: str
+
+
+class ClassStudentEntry(Schema):
+    name: str
+    username: str