Feat: Use one-way data flow to synchronize the form data to the canvas #3221 (#7977)

### What problem does this PR solve?

Feat: Use one-way data flow to synchronize the form data to the canvas
#3221

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/agent/form/begin-form/use-values.ts

@@ -0,0 +1,30 @@
+import { RAGFlowNodeType } from '@/interfaces/database/flow';
+import { isEmpty } from 'lodash';
+import { useMemo } from 'react';
+import { useTranslation } from 'react-i18next';
+import { AgentDialogueMode } from '../../constant';
+
+export function useValues(node?: RAGFlowNodeType) {
+  const { t } = useTranslation();
+
+  const defaultValues = useMemo(
+    () => ({
+      enablePrologue: true,
+      prologue: t('chat.setAnOpenerInitial'),
+      mode: AgentDialogueMode.Conversational,
+    }),
+    [t],
+  );
+
+  const values = useMemo(() => {
+    const formData = node?.data?.form;
+
+    if (isEmpty(formData)) {
+      return defaultValues;
+    }
+
+    return formData;
+  }, [defaultValues, node?.data?.form]);
+
+  return values;
+}