feat: 分站在线充值功能

- 新增 dist_topup.go 控制器，支持易支付/Stripe/Creem/加密货币充值
- 分站模型新增 enable_topup 字段
- 分站前端新增充值页面和导航入口
- 分站设置页新增充值开关
- 添加中英文 i18n 翻译

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/themes/dark/Layout.jsx

@@ -21,6 +21,7 @@ export default function DarkLayout() {
     { to: '/packages', label: t('nav.packages'), auth: false },
     { to: '/dashboard', label: t('nav.dashboard'), auth: true },
     { to: '/tokens', label: t('nav.apiKeys'), auth: true },
+    ...(site?.enable_topup ? [{ to: '/topup', label: t('nav.topup'), auth: true }] : []),
   ];
 
   const visibleNavItems = navItems.filter((n) => !n.auth || user);

src/themes/default/Layout.jsx

@@ -21,6 +21,7 @@ export default function DefaultLayout() {
     { to: '/packages', label: t('nav.packages'), auth: false },
     { to: '/dashboard', label: t('nav.dashboard'), auth: true },
     { to: '/tokens', label: t('nav.apiKeys'), auth: true },
+    ...(site?.enable_topup ? [{ to: '/topup', label: t('nav.topup'), auth: true }] : []),
   ];
 
   const visibleNavItems = navItems.filter((n) => !n.auth || user);

src/themes/minimal/Layout.jsx

@@ -21,6 +21,7 @@ export default function MinimalLayout() {
     { to: '/packages', label: t('nav.packages'), auth: false },
     { to: '/dashboard', label: t('nav.dashboard'), auth: true },
     { to: '/tokens', label: t('nav.apiKeys'), auth: true },
+    ...(site?.enable_topup ? [{ to: '/topup', label: t('nav.topup'), auth: true }] : []),
   ];
 
   const visibleNavItems = navItems.filter((n) => !n.auth || user);

src/themes/starter/Layout.jsx

@@ -21,6 +21,7 @@ export default function StarterLayout() {
     { to: '/packages', label: t('nav.packages'), auth: false },
     { to: '/dashboard', label: t('nav.dashboard'), auth: true },
     { to: '/tokens', label: t('nav.apiKeys'), auth: true },
+    ...(site?.enable_topup ? [{ to: '/topup', label: t('nav.topup'), auth: true }] : []),
   ];
 
   const visibleNavItems = navItems.filter((n) => !n.auth || user);