feat(ui): new WorkflowStartNodeForm using antd

ui/src/utils/cron.ts

@@ -0,0 +1,26 @@
+import { parseExpression } from "cron-parser";
+
+export const validCronExpression = (expr: string): boolean => {
+  try {
+    parseExpression(expr);
+    return true;
+  } catch {
+    return false;
+  }
+};
+
+export const getNextCronExecutions = (expr: string, times = 1): Date[] => {
+  try {
+    const now = new Date();
+    const cron = parseExpression(expr, { currentDate: now, iterator: true });
+
+    const result: Date[] = [];
+    for (let i = 0; i < times; i++) {
+      const next = cron.next();
+      result.push(next.value.toDate());
+    }
+    return result;
+  } catch {
+    return [];
+  }
+};