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/SettlementDetailPage.tsx

@@ -9,6 +9,7 @@ import { useAuthStore } from '../stores/authStore';
 import { formatDateTime, formatRial } from '../lib/utils';
 import StatusBadge from '../components/ui/StatusBadge';
 import ConfirmDialog from '../components/ui/ConfirmDialog';
+import BackButton from '../components/ui/BackButton';
 import Modal from '../components/ui/Modal';
 
 interface SettlementDetail {
@@ -139,9 +140,7 @@ export default function SettlementDetailPage() {
     <div className="fade-in">
       <div className="card-title-row" style={{ marginBottom: 'var(--gap)' }}>
         <div style={{ display: 'flex', alignItems: 'center', gap: 10 }}>
-          <button className="btn ghost sm" onClick={() => navigate('/admin/settlements')} style={{ padding: '6px 10px' }}>
-            <ArrowRightIcon style={{ width: 15, height: 15 }} /> تسویه‌حساب‌ها
-          </button>
+          <BackButton fallback="/admin/settlements" />
           <div>
             <h1 className="section-title">جزئیات تسویه</h1>
             <div className="muted" style={{ fontSize: 13 }}>{s.representation_name}</div>