feat: util for generating client credentials

internal/util/generate.go

@@ -0,0 +1,17 @@
+package util
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+)
+
+// generateRandomStringURLSafe generates a base64 URL-safe random string of n bytes.
+func generateRandomStringURLSafe(n int) (string, error) {
+	bytes := make([]byte, n)
+	_, err := rand.Read(bytes)
+	if err != nil {
+		return "", fmt.Errorf("failed to generate random bytes: %w", err)
+	}
+	return base64.RawURLEncoding.EncodeToString(bytes), nil
+}