feat: implement BackButton component for consistent navigation

- Added BackButton component to standardize back navigation across pages.
- Integrated BackButton into various pages, replacing custom back buttons for consistency.
- Updated PageHeader to accept backTo prop for displaying BackButton when navigating from subpages.
- Created useGoBack hook to handle navigation logic, determining whether to go back in history or redirect to a fallback page.
- Added tests for BackButton and its integration with PageHeader to ensure expected behavior.

assets/admin/pages/ClinicDoctorsPage.tsx

@@ -4,6 +4,7 @@ import { PencilIcon } from '@heroicons/react/24/outline';
 import { useAuthStore } from '../stores/authStore';
 import { usePermissions } from '../hooks/usePermissions';
 import SettingsLayout from '../components/layout/SettingsLayout';
+import BackButton from '../components/ui/BackButton';
 import ClinicDoctorsManager from '../components/ClinicDoctorsManager';
 
 /**
@@ -44,6 +45,9 @@ function ClinicDoctorsContent() {
 
   return (
     <div className="fade-in" style={{ display: 'flex', flexDirection: 'column', gap: 'var(--gap)' }}>
+      <div>
+        <BackButton fallback="/admin/settings-menu" />
+      </div>
       <div className="card-title-row">
         <div>
           <h1 className="section-title">پزشکان کلینیک</h1>