feat(auth): phoneLogin 复用无 openid 的预留成员用户并补 openid

cfc-backend/src/main/java/com/etotem/cfc/service/UserService.java

@@ -209,6 +209,11 @@ private FamilyInvitationService familyInvitationService;
     createUserAndFamily(user);
     try { onboardingService.initForUser(user.getId()); onboardingService.completeTask(user.getId(), "REGISTER"); } catch (Exception e) { /* onboarding init failure should not block login */ }
   } else {
+    // 【重构】预留用户首次登录：补 openid，成为可登录成员
+    if (user.getOpenid() == null || user.getOpenid().isEmpty()) {
+      user.setOpenid("phone:" + phone);
+      user.setRole("parent");
+    }
     // 老用户，更新信息（如果提供了）
     if (dto.getNickname() != null && !dto.getNickname().isEmpty()) {
       user.setNickname(dto.getNickname());