fix score according to claude desktop

sequence-diagram-skill/scripts/score.sh

@@ -30,7 +30,7 @@ fi
 diagram_parseable=0
 if (( has_diagram == 1 )); then
     # Extract mermaid block
-    MERMAID_BLOCK=$(echo "$CONTENT" | sed -n '/```mermaid/,/```/p' | sed '1d;$d')
+    MERMAID_BLOCK=$(echo "$CONTENT" | awk '/^```mermaid/{found=1;next} found && /^```$/{exit} found{print}')
     
     if [[ -n "$MERMAID_BLOCK" ]]; then
         # Basic syntax checks: