新增小程序后端代码，包括数据库、路由、服务层等。

小程序前后端打通，包括登录、注册、绑定设备、查询绑定信息，修改小朋友名称等功能。

mini-program/app/routers/children.py

@@ -0,0 +1,102 @@
+import logging
+
+from fastapi import APIRouter, Depends, HTTPException, Request, status
+from pydantic import BaseModel
+
+try:
+    from app.security import get_current_user_id
+    from app.service.child import ChildService
+    from app.service import get_db_session
+except ModuleNotFoundError:
+    from security import get_current_user_id
+    from service.child import ChildService
+    from service import get_db_session
+
+
+router = APIRouter(prefix="/children", tags=["children"])
+logger = logging.getLogger("app.children")
+
+
+class ChildCreateRequest(BaseModel):
+    child_name: str
+    child_gender: int = 2
+    child_birthday: str | None = None
+
+
+class ChildResponse(BaseModel):
+    child_id: int
+    child_name: str
+    child_gender: int
+    child_birthday: str | None = None
+    status: int
+
+
+class ChildUpdateRequest(BaseModel):
+    child_name: str | None = None
+    child_gender: int | None = None
+    child_birthday: str | None = None
+
+
+class ChildListResponse(BaseModel):
+    items: list[ChildResponse]
+    total: int
+    next_cursor: int | None = None
+
+
+@router.post("", response_model=ChildResponse, status_code=status.HTTP_201_CREATED)
+def create_child(
+    payload: ChildCreateRequest,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> ChildResponse:
+    service = ChildService(db)
+    child = service.create(current_user_id, payload.child_name, payload.child_gender, payload.child_birthday)
+    return ChildResponse(**child)
+
+
+@router.get("", response_model=ChildListResponse)
+def list_children(
+    request: Request,
+    cursor: int | None = None,
+    limit: int = 20,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> ChildListResponse:
+    service = ChildService(db)
+    rows, has_more = service.list_children(current_user_id, limit, cursor)
+    next_cursor = rows[-1]["child_id"] if has_more and rows else None
+    items = [ChildResponse(**row) for row in rows]
+    return ChildListResponse(items=items, total=len(items), next_cursor=next_cursor)
+
+
+@router.get("/{child_id}", response_model=ChildResponse)
+def get_child(
+    child_id: int,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> ChildResponse:
+    service = ChildService(db)
+    child = service.get(child_id)
+    if not child:
+        raise HTTPException(status_code=404, detail="child not found")
+    return ChildResponse(**child)
+
+
+@router.patch("/{child_id}", response_model=ChildResponse)
+def update_child(
+    child_id: int,
+    payload: ChildUpdateRequest,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> ChildResponse:
+    service = ChildService(db)
+    try:
+        child = service.update(child_id, current_user_id, payload.child_name, payload.child_gender, payload.child_birthday)
+    except PermissionError:
+        raise HTTPException(status_code=403, detail="no permission to access this child")
+    if not child:
+        raise HTTPException(status_code=404, detail="child not found")
+    return ChildResponse(**child)