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/bindings.py

@@ -0,0 +1,164 @@
+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.binding import BindingService
+    from app.service import get_db_session
+except ModuleNotFoundError:
+    from security import get_current_user_id
+    from service.binding import BindingService
+    from service import get_db_session
+
+
+router = APIRouter(prefix="/bindings", tags=["bindings"])
+logger = logging.getLogger("app.bindings")
+
+
+class BindStartRequest(BaseModel):
+    device_id: str
+    child_id: int
+
+
+class BindStartResponse(BaseModel):
+    bind_token: str
+    expires_at: str
+
+
+class BindConfirmRequest(BaseModel):
+    bind_token: str
+    challenge_code: str
+
+
+class BindConfirmResponse(BaseModel):
+    device_id: str
+    child_id: int
+
+
+class BindingGetResponse(BaseModel):
+    device_id: str
+    child_id: int
+    status: int
+    bound_at: str
+
+
+class BindHistoryItem(BaseModel):
+    device_id: str
+    child_id: int
+    bound_at: str
+    unbound_at: str | None
+
+
+class BindHistoryResponse(BaseModel):
+    items: list[BindHistoryItem]
+    total: int
+    next_cursor: str | None
+
+
+@router.post("/start", response_model=BindStartResponse)
+def start_bind(
+    payload: BindStartRequest,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> BindStartResponse:
+    service = BindingService(db)
+    bind_token, expires_at = service.start_bind(current_user_id, payload.device_id, payload.child_id)
+    return BindStartResponse(bind_token=bind_token, expires_at=expires_at.isoformat())
+
+
+@router.post("/confirm", response_model=BindConfirmResponse)
+def confirm_bind(
+    payload: BindConfirmRequest,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> BindConfirmResponse:
+    service = BindingService(db)
+    try:
+        result = service.confirm_bind(payload.bind_token, current_user_id)
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    return BindConfirmResponse(**result)
+
+
+class DirectBindRequest(BaseModel):
+    device_id: str
+    child_id: int
+
+
+class DirectBindResponse(BaseModel):
+    device_id: str
+    child_id: int
+
+
+@router.post("/direct", response_model=DirectBindResponse)
+def direct_bind(
+    payload: DirectBindRequest,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> DirectBindResponse:
+    service = BindingService(db)
+    result = service.direct_bind(payload.device_id, payload.child_id, current_user_id)
+    return DirectBindResponse(**result)
+
+
+@router.get("/current", response_model=BindingGetResponse)
+def get_current_binding(
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+):
+    service = BindingService(db)
+    binding = service.get_current_binding(current_user_id)
+    if not binding:
+        raise HTTPException(status_code=404, detail="no binding found")
+    return binding
+
+
+@router.get("/{device_id}", response_model=BindingGetResponse)
+def get_binding(
+    device_id: str,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> BindingGetResponse:
+    service = BindingService(db)
+    binding = service.get_binding(device_id, current_user_id)
+    if not binding:
+        raise HTTPException(status_code=404, detail="binding not found")
+    return BindingGetResponse(**binding)
+
+
+@router.delete("/{device_id}", status_code=status.HTTP_204_NO_CONTENT)
+def unbind_device(
+    device_id: str,
+    request: Request,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> None:
+    service = BindingService(db)
+    if not service.unbind(device_id, current_user_id):
+        raise HTTPException(status_code=404, detail="binding not found")
+
+
+@router.get("/history/{device_id}", response_model=BindHistoryResponse)
+def get_bind_history(
+    device_id: str,
+    request: Request,
+    cursor: str | None = None,
+    limit: int = 20,
+    current_user_id: int = Depends(get_current_user_id),
+    db=Depends(get_db_session),
+) -> BindHistoryResponse:
+    from datetime import datetime
+
+    cursor_dt = datetime.fromisoformat(cursor) if cursor else None
+    service = BindingService(db)
+    rows, has_more = service.list_history(device_id, limit, cursor_dt)
+    next_cursor = rows[-1]["bound_at"].isoformat() if has_more and rows else None
+    items = [BindHistoryItem(**row) for row in rows]
+    return BindHistoryResponse(items=items, total=len(items), next_cursor=next_cursor)