refactor: move secretary and staff management from main nav to settings menu

Remove پرسنل (/admin/staff) and منشی ها (/admin/my-secretaries) from the
clinic and doctor main sidebars; surface them under the settings menu instead
(PurchaseSubscriptionSidebar + SETTINGS_MENU). Wrap StaffPage in SettingsLayout
so it renders inside the settings shell like MySecretariesPage already does.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/admin/components/layout/Sidebar.tsx

@@ -13,7 +13,6 @@ import {
     DocumentTextIcon,
     FolderOpenIcon,
     HeartIcon,
-    IdentificationIcon,
     KeyIcon,
     LockClosedIcon,
     ShieldCheckIcon,
@@ -21,7 +20,6 @@ import {
     TagIcon,
     UserCircleIcon,
     UserGroupIcon,
-    UserPlusIcon,
     UsersIcon,
 } from "@heroicons/react/24/outline";
 import { NavLink, useNavigate } from "react-router-dom";
@@ -224,12 +222,6 @@ function buildSections(
                         label: "مطالبات بیمه",
                         feature: "insurance",
                     },
-                    { to: "/admin/staff", icon: UserPlusIcon, label: "پرسنل" },
-                    {
-                        to: "/admin/my-secretaries",
-                        icon: IdentificationIcon,
-                        label: "منشی ها",
-                    },
                 ],
             },
             {
@@ -294,12 +286,6 @@ function buildSections(
                         label: "مطالبات بیمه",
                         feature: "insurance",
                     },
-                    { to: "/admin/staff", icon: UserPlusIcon, label: "پرسنل" },
-                    {
-                        to: "/admin/my-secretaries",
-                        icon: IdentificationIcon,
-                        label: "منشی ها",
-                    },
                 ],
             },
             {