feat: add event filter to skip closed issues in handle-issue-ts.sh

Added check to skip Claude Agent SDK execution when issue action is 'closed'.
This prevents unnecessary processing when issues are closed, but still allows
execution when issues are reopened.

Resolves #11

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/handle-issue-ts.sh

@@ -43,6 +43,12 @@ if [ "$ASSIGNEE" != "claude" ]; then
     exit 0
 fi
 
+# Exit if issue action is 'closed' (but allow 'reopened')
+if [ "$ISSUE_ACTION" = "closed" ]; then
+    echo "Issue action is 'closed', skipping automation"
+    exit 0
+fi
+
 # Determine repo path
 REPO_PATH="$HOME/$REPO"