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/ClinicDetailPage.tsx

@@ -578,13 +578,11 @@ export default function ClinicDetailPage() {
 
       {/* ── Header ── */}
       <PageHeader
+        backTo="/admin/clinics"
         title={clinicName}
         breadcrumbs={[{ label: 'کلینیک‌ها', to: '/admin/clinics' }, { label: clinicName }]}
         action={
           <div style={{ display: 'flex', gap: 8, flexWrap: 'wrap', justifyContent: 'flex-end' }}>
-            <button className="btn ghost sm" onClick={() => navigate('/admin/clinics')}>
-              <ArrowRightIcon style={{ width: 15, height: 15 }} /> بازگشت
-            </button>
             {!isReadOnly && (
               <button className="btn soft sm" onClick={() => openEdit()}>
                 <PencilIcon style={{ width: 15, height: 15 }} /> ویرایش