feat: port payment management tab from tauri to admin dashboard

Add per-clinic payment methods (bank accounts + POS/card-reader devices)
under the "مدیریت پرداخت" settings tab at /admin/my-financial, ported from
clinic-pro-tauri's mock-only PaymentManagement tab into a real persisted
feature. These records are referenceable (by uuid) from patient invoices to
record which method a service payment was made with.

Backend (new src/PaymentMethod domain):
- BankAccount + Pos entities, repositories, PaymentMethodService (validation,
  ownership scoping, create/update/toggle logic).
- Thin PaymentMethodController exposing /api/v1/my/payment-methods/{bank-accounts,pos}
  (GET/POST/PUT + PATCH .../status), guarded to clinic/doctor/secretary/admin.
- Migration for bank_accounts + pos_devices tables.
- Functional tests (success + validation/404/403 + empty boundaries).
- docs/api/payment-method.md.

Frontend:
- Replace MyFinancialPage content with the payment-management UI (two tabs,
  tables, add/edit modals, status toggle) using the admin design system.
- usePaymentMethods hook (TanStack Query) + presentational components.
- Update page test to cover tabs, data, empty state and the add modal.

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

assets/admin/components/paymentMethods/PosTable.tsx

@@ -0,0 +1,67 @@
+import React from 'react';
+import { PencilIcon } from '@heroicons/react/24/outline';
+import DataTable, { type Column } from '../ui/DataTable';
+import StatusToggle from './StatusToggle';
+import type { Pos } from '../../hooks/usePaymentMethods';
+
+/**
+ * جدول کارت‌خوان‌ها — پورت مبدأ PoseList.jsx.
+ * ستون‌ها: نام بانک، شماره سریال، شماره ترمینال، وضعیت، عملیات.
+ */
+export default function PosTable({
+  data,
+  loading,
+  togglingUuid,
+  onToggle,
+  onEdit,
+  onAdd,
+}: {
+  data: Pos[];
+  loading?: boolean;
+  togglingUuid: string | null;
+  onToggle: (uuid: string) => void;
+  onEdit: (pos: Pos) => void;
+  onAdd: () => void;
+}) {
+  const columns: Column<Pos>[] = [
+    { key: 'bank_name', header: 'نام بانک' },
+    { key: 'serial_number', header: 'شماره سریال', render: (r) => r.serial_number || '—' },
+    { key: 'terminal_number', header: 'شماره ترمینال', render: (r) => r.terminal_number || '—' },
+    {
+      key: 'is_active',
+      header: 'وضعیت',
+      render: (r) => (
+        <StatusToggle
+          active={r.is_active}
+          disabled={togglingUuid === r.uuid}
+          onToggle={() => onToggle(r.uuid)}
+        />
+      ),
+    },
+  ];
+
+  return (
+    <>
+      <p style={{ fontSize: 13.5, color: 'var(--text-2)', margin: '0 0 14px' }}>
+        مدیریت و اضافه کردن دستگاه های کارت خوان موجود
+      </p>
+      <DataTable<Pos>
+        columns={columns}
+        data={data}
+        loading={loading}
+        emptyMessage="هنوز کارت خوانی ثبت نشده است"
+        emptyAction={<button className="btn primary sm" onClick={onAdd}>افزودن کارت خوان</button>}
+        actions={(r) => (
+          <button
+            className="btn sm ghost"
+            style={{ color: 'var(--accent)' }}
+            onClick={() => onEdit(r)}
+          >
+            <PencilIcon style={{ width: 14 }} />
+            ویرایش
+          </button>
+        )}
+      />
+    </>
+  );
+}