feat(numx): 自 go-hua/common 迁入数值工具并独立成包

- 流量格式化、低位取整、多整数取最值(Max/Min 自 version.go 归位)
- 附单元测试、examples/numx 例程与包 README

numx/numx_test.go

@@ -0,0 +1,38 @@
+package numx
+
+import "testing"
+
+func TestFormatFlow(t *testing.T) {
+	cases := []struct {
+		in   int64
+		want string
+	}{
+		{500, "500 B"},
+		{1536, "1.5 KB"},
+		{1024 * 1024, "1.0 MB"},
+		{1024 * 1024 * 1024, "1.0 GB"},
+	}
+	for _, c := range cases {
+		if got := FormatFlow(c.in); got != c.want {
+			t.Errorf("FormatFlow(%d) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}
+
+func TestIgnoreDigits(t *testing.T) {
+	if got := IgnoreDigits(12345, 3); got != 12000 {
+		t.Errorf("IgnoreDigits(12345,3) = %d, want 12000", got)
+	}
+}
+
+func TestMaxMin(t *testing.T) {
+	if got := Max(3, 7, 5); got != 7 {
+		t.Errorf("Max = %d, want 7", got)
+	}
+	if got := Min(3, 1, 2); got != 1 {
+		t.Errorf("Min = %d, want 1", got)
+	}
+	if got := Min(2, 5); got != 2 {
+		t.Errorf("Min(2,5) = %d, want 2", got)
+	}
+}