feat: Add Resend node and trigger

Adds a new integration for Resend, an email sending service.

Includes:
- Resend API credential (`ResendApi.credentials.ts`) for API key authentication.
- Resend action node (`nodes/Resend/Resend.node.ts`):
  - Supports "Send Email" operation with parameters for to, from, subject, html, text, cc, bcc, reply_to, and tags.
  - Uses Resend API `https://api.resend.com/emails`.
- Resend trigger node (`nodes/Resend/ResendTrigger.node.ts`):
  - Handles Resend webhooks for various event types (email.sent, email.delivered, etc.).
  - Implements webhook signature verification using Svix and a user-provided signing secret.
  - Allows you to select which events to listen for.
- Official Resend SVG icon (`nodes/Resend/Resend.svg`).
- Adds `svix` as a dependency for webhook verification.

nodes/Resend/Resend.node.ts

@@ -0,0 +1,267 @@
+import {
+	IExecuteFunctions,
+	INodeExecutionData,
+	INodeType,
+	INodeTypeDescription,
+	NodeOperationError,
+} from 'n8n-workflow';
+
+export class Resend implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'Resend',
+		name: 'resend',
+		icon: 'file:Resend.svg',
+		group: ['output'],
+		version: 1,
+		description: 'Sends emails via Resend API',
+		defaults: {
+			name: 'Resend',
+			color: '#000000',
+		},
+		credentials: [
+			{
+				name: 'resendApi',
+				required: true,
+			},
+		],
+		inputs: ['main'],
+		outputs: ['main'],
+		properties: [
+			{
+				displayName: 'Operation',
+				name: 'operation',
+				type: 'options',
+				noDataExpression: true,
+				options: [
+					{
+						name: 'Send Email',
+						value: 'sendEmail',
+						action: 'Send an email',
+						routing: {
+							request: {
+								method: 'POST',
+								url: 'https://api.resend.com/emails',
+							},
+						},
+					},
+				],
+				default: 'sendEmail',
+			},
+			// Properties for "Send Email" operation
+			{
+				displayName: 'From',
+				name: 'fromEmail',
+				type: 'string',
+				required: true,
+				default: '',
+				placeholder: 'you@example.com',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Sender email address',
+			},
+			{
+				displayName: 'To',
+				name: 'toEmail',
+				type: 'string',
+				required: true,
+				default: '',
+				placeholder: 'user@example.com',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Comma-separated list of recipient email addresses',
+			},
+			{
+				displayName: 'Subject',
+				name: 'subject',
+				type: 'string',
+				required: true,
+				default: '',
+				placeholder: 'Hello from n8n!',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+			},
+			{
+				displayName: 'HTML',
+				name: 'htmlBody',
+				type: 'string',
+				required: true,
+				default: '',
+				typeOptions: {
+					multiline: true,
+				},
+				placeholder: '<p>Your HTML content here</p>',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+			},
+			{
+				displayName: 'Text',
+				name: 'textBody',
+				type: 'string',
+				default: '',
+				placeholder: 'Your plain text content here',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Plain text content of the email (optional)',
+			},
+			{
+				displayName: 'CC',
+				name: 'ccEmail',
+				type: 'string',
+				default: '',
+				placeholder: 'cc@example.com',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Comma-separated list of CC email addresses',
+			},
+			{
+				displayName: 'BCC',
+				name: 'bccEmail',
+				type: 'string',
+				default: '',
+				placeholder: 'bcc@example.com',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Comma-separated list of BCC email addresses',
+			},
+			{
+				displayName: 'Reply To',
+				name: 'replyToEmail',
+				type: 'string',
+				default: '',
+				placeholder: 'reply@example.com',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				description: 'Email address to set as reply-to',
+			},
+			{
+				displayName: 'Tags',
+				name: 'tags',
+				type: 'fixedCollection',
+				typeOptions: {
+					multipleValues: true,
+				},
+				default: {},
+				placeholder: 'Add Tag',
+				displayOptions: {
+					show: {
+						operation: ['sendEmail'],
+					},
+				},
+				properties: [
+					{
+						name: 'tag',
+						displayName: 'Tag',
+						values: [
+							{
+								displayName: 'Name',
+								name: 'name',
+								type: 'string',
+								default: '',
+							},
+							{
+								displayName: 'Value',
+								name: 'value',
+								type: 'string',
+								default: '',
+							},
+						],
+					},
+				],
+				description: 'Tags to categorize the email',
+			},
+		],
+	};
+
+	async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
+		const items = this.getInputData();
+		const returnData: INodeExecutionData[] = [];
+		const length = items.length;
+
+		for (let i = 0; i < length; i++) {
+			try {
+				const operation = this.getNodeParameter('operation', i) as string;
+				const credentials = await this.getCredentials('resendApi');
+				const apiKey = credentials.apiKey as string;
+
+				if (operation === 'sendEmail') {
+					const fromEmail = this.getNodeParameter('fromEmail', i) as string;
+					const toEmail = this.getNodeParameter('toEmail', i) as string;
+					const subject = this.getNodeParameter('subject', i) as string;
+					const htmlBody = this.getNodeParameter('htmlBody', i) as string;
+					const textBody = this.getNodeParameter('textBody', i, '') as string;
+					const ccEmail = this.getNodeParameter('ccEmail', i, '') as string;
+					const bccEmail = this.getNodeParameter('bccEmail', i, '') as string;
+					const replyToEmail = this.getNodeParameter('replyToEmail', i, '') as string;
+					const tagsData = this.getNodeParameter('tags', i, { tag: [] }) as { tag: Array<{ name: string; value: string }> };
+
+					const requestBody: any = {
+						from: fromEmail,
+						to: toEmail.split(',').map(email => email.trim()).filter(email => email),
+						subject: subject,
+						html: htmlBody,
+					};
+
+					if (textBody) {
+						requestBody.text = textBody;
+					}
+					if (ccEmail) {
+						requestBody.cc = ccEmail.split(',').map(email => email.trim()).filter(email => email);
+					}
+					if (bccEmail) {
+						requestBody.bcc = bccEmail.split(',').map(email => email.trim()).filter(email => email);
+					}
+					if (replyToEmail) {
+						requestBody.reply_to = replyToEmail;
+					}
+					if (tagsData.tag && tagsData.tag.length > 0) {
+						requestBody.tags = tagsData.tag.map(t => ({ name: t.name, value: t.value }));
+					}
+
+					const response = await this.helpers.httpRequest({
+						url: 'https://api.resend.com/emails',
+						method: 'POST',
+						headers: {
+							Authorization: `Bearer ${apiKey}`,
+							'Content-Type': 'application/json',
+						},
+						body: requestBody,
+						json: true,
+					});
+
+					returnData.push({ json: response, pairedItem: { item: i } });
+				}
+			} catch (error) {
+				if (this.continueOnFail()) {
+					returnData.push({ json: { error: error.message }, pairedItem: { item: i } });
+					continue;
+				}
+				throw new NodeOperationError(this.getNode(), error);
+			}
+		}
+		return [returnData];
+	}
+}