学生资料设置、头像与自动备份恢复。

首页卡片支持修改/删除；详情页设置 Tab 可维护学校、年级与头像；系统设置新增数据备份下载与恢复；备份默认存 /root/grade-archive-backups，详见 docs/BACKUP.md。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/schemas/__init__.py

@@ -136,6 +136,7 @@ class StudentCreate(BaseModel):
     school_level: SchoolLevelEnum = SchoolLevelEnum.junior_high
     grade: str | None = None
     class_name: str | None = None
+    school_name: str | None = Field(default=None, max_length=128)
 
 
 class StudentUpdate(BaseModel):
@@ -143,6 +144,7 @@ class StudentUpdate(BaseModel):
     school_level: SchoolLevelEnum | None = None
     grade: str | None = None
     class_name: str | None = None
+    school_name: str | None = Field(default=None, max_length=128)
 
 
 class StudentOut(BaseModel):
@@ -151,10 +153,25 @@ class StudentOut(BaseModel):
     school_level: SchoolLevelEnum
     grade: str | None
     class_name: str | None
+    school_name: str | None
+    has_avatar: bool = False
     created_at: datetime
 
     model_config = {"from_attributes": True}
 
+    @classmethod
+    def from_student(cls, student) -> "StudentOut":
+        return cls(
+            id=student.id,
+            name=student.name,
+            school_level=SchoolLevelEnum(student.school_level.value),
+            grade=student.grade,
+            class_name=student.class_name,
+            school_name=student.school_name,
+            has_avatar=bool(getattr(student, "avatar_path", None)),
+            created_at=student.created_at,
+        )
+
 
 class SubjectOut(BaseModel):
     id: int
@@ -335,3 +352,9 @@ class CompositionOut(BaseModel):
     updated_at: datetime
 
     model_config = {"from_attributes": True}
+
+
+class BackupInfoOut(BaseModel):
+    filename: str
+    size_bytes: int
+    created_at: datetime