feat(backend,frontend): enable quotas support in bucket settings (#64)

frontend/src/lib/quota-utils.ts

@@ -0,0 +1,33 @@
+export type QuotaUnit = 'MB' | 'GB' | 'TB';
+
+export const QUOTA_UNIT_BYTES: Record<QuotaUnit, number> = {
+  MB: 1024 * 1024,
+  GB: 1024 * 1024 * 1024,
+  TB: 1024 * 1024 * 1024 * 1024,
+};
+
+// Convert a byte count to a {value, unit} pair using the largest unit that
+// yields an integer. Falls back to GB if the value is 0 or doesn't divide
+// evenly into any unit.
+export function bytesToQuotaValue(bytes: number): { value: number; unit: QuotaUnit } {
+  const units: QuotaUnit[] = ['TB', 'GB', 'MB'];
+  for (const unit of units) {
+    const factor = QUOTA_UNIT_BYTES[unit];
+    if (bytes >= factor && bytes % factor === 0) {
+      return { value: bytes / factor, unit };
+    }
+  }
+  // Doesn't divide evenly — pick the largest unit where the value is >= 1,
+  // rounded for display. The user is free to change it.
+  for (const unit of units) {
+    const factor = QUOTA_UNIT_BYTES[unit];
+    if (bytes >= factor) {
+      return { value: Math.round((bytes / factor) * 100) / 100, unit };
+    }
+  }
+  return { value: 0, unit: 'GB' };
+}
+
+export function quotaValueToBytes(value: number, unit: QuotaUnit): number {
+  return Math.round(value * QUOTA_UNIT_BYTES[unit]);
+}