feat: validate user input for entity names

internal/number/number.go

@@ -1,6 +1,9 @@
 package number
 
-import "math"
+import (
+	"cmp"
+	"math"
+)
 
 func Fixed3(num float64) float64 {
 	return fixed(num, 3)
@@ -18,3 +21,10 @@ func fixed(num float64, precision int) float64 {
 func round(num float64) int {
 	return int(num + math.Copysign(0.5, num))
 }
+
+func Max[T cmp.Ordered](x, y T) T {
+	if cmp.Compare(x, y) == 1 {
+		return x
+	}
+	return y
+}