✨ feat: add subscription billing system with admin management and user purchase flow

Implement a new subscription-based billing model alongside existing metered/per-request billing:

Backend:
- Add subscription plan models (SubscriptionPlan, SubscriptionPlanItem, UserSubscription, etc.)
- Implement CRUD APIs for subscription plan management (admin only)
- Add user subscription queries with support for multiple active/expired subscriptions
- Integrate payment gateways (Stripe, Creem, Epay) for subscription purchases
- Implement pre-consume and post-consume billing logic for subscription quota tracking
- Add billing preference settings (subscription_first, wallet_first, etc.)
- Enhance usage logs with subscription deduction details

Frontend - Admin:
- Add subscription management page with table view and drawer-based edit form
- Match UI/UX style with existing admin pages (redemption codes, users)
- Support enabling/disabling plans, configuring payment IDs, and model quotas
- Add user subscription binding modal in user management

Frontend - Wallet:
- Add subscription plans card with current subscription status display
- Show all subscriptions (active and expired) with remaining days/usage percentage
- Display purchasable plans with pricing cards following SaaS best practices
- Extract purchase modal to separate component matching payment confirm modal style
- Add skeleton loading states with active animation
- Implement billing preference selector in card header
- Handle payment gateway availability based on admin configuration

Frontend - Usage Logs:
- Display subscription deduction details in log entries
- Show step-by-step breakdown of subscription usage (pre-consumed, delta, final, remaining)
- Add subscription deduction tag for subscription-covered requests

web/src/components/table/subscriptions/SubscriptionsTable.jsx

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+/*
+Copyright (C) 2025 QuantumNous
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+For commercial licensing, please contact support@quantumnous.com
+*/
+
+import React, { useMemo } from 'react';
+import { Empty } from '@douyinfe/semi-ui';
+import CardTable from '../../common/ui/CardTable';
+import {
+  IllustrationNoResult,
+  IllustrationNoResultDark,
+} from '@douyinfe/semi-illustrations';
+import { getSubscriptionsColumns } from './SubscriptionsColumnDefs';
+
+const SubscriptionsTable = (subscriptionsData) => {
+  const {
+    plans,
+    loading,
+    compactMode,
+    openEdit,
+    disablePlan,
+    t,
+  } = subscriptionsData;
+
+  const columns = useMemo(() => {
+    return getSubscriptionsColumns({
+      t,
+      openEdit,
+      disablePlan,
+    });
+  }, [t, openEdit, disablePlan]);
+
+  const tableColumns = useMemo(() => {
+    return compactMode
+      ? columns.map((col) => {
+        if (col.dataIndex === 'operate') {
+          const { fixed, ...rest } = col;
+          return rest;
+        }
+        return col;
+      })
+      : columns;
+  }, [compactMode, columns]);
+
+  return (
+    <CardTable
+      columns={tableColumns}
+      dataSource={plans}
+      scroll={compactMode ? undefined : { x: 'max-content' }}
+      pagination={false}
+      hidePagination={true}
+      loading={loading}
+      rowKey={(row) => row?.plan?.id}
+      empty={
+        <Empty
+          image={<IllustrationNoResult style={{ width: 150, height: 150 }} />}
+          darkModeImage={
+            <IllustrationNoResultDark style={{ width: 150, height: 150 }} />
+          }
+          description={t('暂无订阅套餐')}
+          style={{ padding: 30 }}
+        />
+      }
+      className='overflow-hidden'
+      size='middle'
+    />
+  );
+};
+
+export default SubscriptionsTable;