Email sending tool (#3837)

### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._
Added the function of sending emails through SMTP
Instructions for use-
Corresponding parameters need to be configured
Need to output upstream in a fixed format

![image](https://github.com/user-attachments/assets/93bc1af7-6d4f-4406-bd1d-bc042535dd82)


### Type of change


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

---------

Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

web/src/pages/flow/constant.tsx

@@ -8,6 +8,7 @@ import { ReactComponent as ConcentratorIcon } from '@/assets/svg/concentrator.sv
 import { ReactComponent as CrawlerIcon } from '@/assets/svg/crawler.svg';
 import { ReactComponent as DeepLIcon } from '@/assets/svg/deepl.svg';
 import { ReactComponent as DuckIcon } from '@/assets/svg/duck.svg';
+import { ReactComponent as EmailIcon } from '@/assets/svg/email.svg';
 import { ReactComponent as ExeSqlIcon } from '@/assets/svg/exesql.svg';
 import { ReactComponent as GithubIcon } from '@/assets/svg/github.svg';
 import { ReactComponent as GoogleScholarIcon } from '@/assets/svg/google-scholar.svg';
@@ -25,6 +26,8 @@ import { ReactComponent as WenCaiIcon } from '@/assets/svg/wencai.svg';
 import { ReactComponent as WikipediaIcon } from '@/assets/svg/wikipedia.svg';
 import { ReactComponent as YahooFinanceIcon } from '@/assets/svg/yahoo-finance.svg';
 
+// 邮件功能
+
 import { variableEnabledFieldMap } from '@/constants/chat';
 import i18n from '@/locales/config';
 
@@ -87,6 +90,7 @@ export enum Operator {
   Crawler = 'Crawler',
   Invoke = 'Invoke',
   Template = 'Template',
+  Email = 'Email',
 }
 
 export const CommonOperatorList = Object.values(Operator).filter(
@@ -127,6 +131,7 @@ export const operatorIconMap = {
   [Operator.Crawler]: CrawlerIcon,
   [Operator.Invoke]: InvokeIcon,
   [Operator.Template]: TemplateIcon,
+  [Operator.Email]: EmailIcon,
 };
 
 export const operatorMap: Record<
@@ -259,6 +264,7 @@ export const operatorMap: Record<
   [Operator.Template]: {
     backgroundColor: '#dee0e2',
   },
+  [Operator.Email]: { backgroundColor: '#e6f7ff' },
 };
 
 export const componentMenuList = [
@@ -358,6 +364,9 @@ export const componentMenuList = [
   {
     name: Operator.Invoke,
   },
+  {
+    name: Operator.Email,
+  },
 ];
 
 const initialQueryBaseValues = {
@@ -580,6 +589,18 @@ export const initialTemplateValues = {
   parameters: [],
 };
 
+export const initialEmailValues = {
+  smtp_server: '',
+  smtp_port: 587,
+  email: '',
+  password: '',
+  sender_name: '',
+  to_email: '',
+  cc_email: '',
+  subject: '',
+  content: '',
+};
+
 export const CategorizeAnchorPointPositions = [
   { top: 1, right: 34 },
   { top: 8, right: 18 },
@@ -660,6 +681,7 @@ export const RestrictedUpstreamMap = {
   [Operator.Note]: [],
   [Operator.Invoke]: [Operator.Begin],
   [Operator.Template]: [Operator.Begin, Operator.Relevant],
+  [Operator.Email]: [Operator.Begin],
 };
 
 export const NodeMap = {
@@ -696,6 +718,7 @@ export const NodeMap = {
   [Operator.Crawler]: 'ragNode',
   [Operator.Invoke]: 'invokeNode',
   [Operator.Template]: 'templateNode',
+  [Operator.Email]: 'emailNode',
 };
 
 export const LanguageOptions = [