Implement compression quota refunds and admin manual subscription

frontend/src/utils/format.ts

@@ -0,0 +1,23 @@
+export function formatBytes(bytes: number): string {
+  if (!Number.isFinite(bytes) || bytes <= 0) return '0 B'
+  const units = ['B', 'KB', 'MB', 'GB']
+  let value = bytes
+  let unit = 0
+  while (value >= 1024 && unit < units.length - 1) {
+    value /= 1024
+    unit += 1
+  }
+  const digits = unit === 0 ? 0 : unit === 1 ? 1 : 2
+  return `${value.toFixed(digits)} ${units[unit]}`
+}
+
+export function formatCents(amountCents: number, currency: string): string {
+  const amount = (amountCents ?? 0) / 100
+  const cc = (currency ?? 'CNY').toUpperCase()
+  return new Intl.NumberFormat('zh-CN', {
+    style: 'currency',
+    currency: cc,
+    maximumFractionDigits: 2,
+  }).format(amount)
+}
+