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/parents.py

@@ -0,0 +1,63 @@
+import logging
+
+from fastapi import APIRouter, Depends, HTTPException, Request, status
+from pydantic import BaseModel
+
+try:
+    from app.service.parent import ParentService
+    from app.service import get_db_session
+except ModuleNotFoundError:
+    from service.parent import ParentService
+    from service import get_db_session
+
+
+router = APIRouter(prefix="/parents", tags=["parents"])
+logger = logging.getLogger("app.parents")
+
+
+class ParentCreateRequest(BaseModel):
+    openid: str
+    unionid: str | None = None
+    nickname: str | None = None
+    avatar_url: str | None = None
+
+
+class ParentResponse(BaseModel):
+    user_id: int
+    openid: str
+    unionid: str | None = None
+    nickname: str | None = None
+    avatar_url: str | None = None
+    phone: str | None = None
+    status: int
+
+
+class ParentUpdateRequest(BaseModel):
+    nickname: str | None = None
+    avatar_url: str | None = None
+    phone: str | None = None
+
+
+@router.post("", response_model=ParentResponse, status_code=status.HTTP_201_CREATED)
+def create_parent(payload: ParentCreateRequest, request: Request, db=Depends(get_db_session)) -> ParentResponse:
+    service = ParentService(db)
+    parent = service.create(payload.openid, payload.unionid, payload.nickname, payload.avatar_url)
+    return ParentResponse(**parent)
+
+
+@router.get("/{user_id}", response_model=ParentResponse)
+def get_parent(user_id: int, request: Request, db=Depends(get_db_session)) -> ParentResponse:
+    service = ParentService(db)
+    parent = service.get(user_id)
+    if not parent:
+        raise HTTPException(status_code=404, detail="parent not found")
+    return ParentResponse(**parent)
+
+
+@router.patch("/{user_id}", response_model=ParentResponse)
+def update_parent(user_id: int, payload: ParentUpdateRequest, request: Request, db=Depends(get_db_session)) -> ParentResponse:
+    service = ParentService(db)
+    parent = service.update(user_id, payload.nickname, payload.avatar_url, payload.phone)
+    if not parent:
+        raise HTTPException(status_code=404, detail="parent not found")
+    return ParentResponse(**parent)