docs+ui: add bilingual payment integration doc and rename purchase entry to recharge/subscription

frontend/src/components/layout/AppSidebar.vue

@@ -290,6 +290,26 @@ const CreditCardIcon = {
     )
 }
 
+const RechargeSubscriptionIcon = {
+  render: () =>
+    h(
+      'svg',
+      { fill: 'none', viewBox: '0 0 24 24', stroke: 'currentColor', 'stroke-width': '1.5' },
+      [
+        h('path', {
+          'stroke-linecap': 'round',
+          'stroke-linejoin': 'round',
+          d: 'M2.25 7.5A2.25 2.25 0 014.5 5.25h15A2.25 2.25 0 0121.75 7.5v9A2.25 2.25 0 0119.5 18.75h-15A2.25 2.25 0 012.25 16.5v-9z'
+        }),
+        h('path', {
+          'stroke-linecap': 'round',
+          'stroke-linejoin': 'round',
+          d: 'M6.75 12h3m4.5 0h3m-3-3v6'
+        })
+      ]
+    )
+}
+
 const GlobeIcon = {
   render: () =>
     h(
@@ -490,7 +510,7 @@ const userNavItems = computed(() => {
           {
             path: '/purchase',
             label: t('nav.buySubscription'),
-            icon: CreditCardIcon,
+            icon: RechargeSubscriptionIcon,
             hideInSimpleMode: true
           }
         ]
@@ -515,7 +535,7 @@ const personalNavItems = computed(() => {
           {
             path: '/purchase',
             label: t('nav.buySubscription'),
-            icon: CreditCardIcon,
+            icon: RechargeSubscriptionIcon,
             hideInSimpleMode: true
           }
         ]