feat: deduplicate ship name on transfer

internal/util/string_test.go

@@ -1,6 +1,7 @@
 package util_test
 
 import (
+	"strings"
 	"testing"
 	"unicode/utf8"
 
@@ -238,3 +239,54 @@ func FuzzValidateString(f *testing.F) {
 		}
 	})
 }
+
+func TestAppendRandomSuffixGenerator(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		suffix   string
+		expected string
+	}{
+		{
+			name:     "Regular String",
+			input:    "Regular_String",
+			suffix:   "1234",
+			expected: "Regular_String1234",
+		},
+		{
+			name:     "Zero Length String",
+			input:    "",
+			suffix:   "1234",
+			expected: "1234",
+		},
+		{
+			name:     "Edge Case String len=28",
+			input:    "Edge_Case_String_ABCDEFGHIGK",
+			suffix:   "1234",
+			expected: "Edge_Case_String_ABCDEFGHI1234",
+		},
+		{
+			name:     "Extra Long String len=31",
+			input:    "Extra_Long_String_ABCDEFGHIGKLM",
+			suffix:   "1234",
+			expected: "Extra_Long_String_ABCDEFGH1234",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := util.AppendRandomSuffixGenerator(tt.input, func() string { return tt.suffix })
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestRandomSuffixGenerator(t *testing.T) {
+	var last string
+	for range 100 {
+		s := util.RandomSuffixGenerator()
+		assert.Len(t, s, 4)
+		assert.NotEqual(t, last, s)
+		assert.True(t, strings.ContainsFunc(s, func(r rune) bool { return r >= '0' && r <= '9' }))
+		last = s
+	}
+}