feat: docker compose backup

internal/backup/format.go

@@ -0,0 +1,17 @@
+package backup
+
+import "fmt"
+
+// FormatSize formats a byte count as a human-readable string.
+func FormatSize(n int64) string {
+	const unit = 1024
+	if n < unit {
+		return fmt.Sprintf("%d B", n)
+	}
+	div, exp := int64(unit), 0
+	for b := n / unit; b >= unit; b /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %cB", float64(n)/float64(div), "KMGTPE"[exp])
+}