feat(Chat Trigger Node): Add support for file uploads & harmonize public and development chat (#9802)

Signed-off-by: Oleg Ivaniv <me@olegivaniv.com>

packages/@n8n/chat/src/api/message.ts

@@ -1,4 +1,4 @@
-import { get, post } from '@n8n/chat/api/generic';
+import { get, post, postWithFiles } from '@n8n/chat/api/generic';
 import type {
 	ChatOptions,
 	LoadPreviousSessionResponse,
@@ -20,7 +20,27 @@ export async function loadPreviousSession(sessionId: string, options: ChatOption
 	);
 }
 
-export async function sendMessage(message: string, sessionId: string, options: ChatOptions) {
+export async function sendMessage(
+	message: string,
+	files: File[],
+	sessionId: string,
+	options: ChatOptions,
+) {
+	if (files.length > 0) {
+		return await postWithFiles<SendMessageResponse>(
+			`${options.webhookUrl}`,
+			{
+				action: 'sendMessage',
+				[options.chatSessionKey as string]: sessionId,
+				[options.chatInputKey as string]: message,
+				...(options.metadata ? { metadata: options.metadata } : {}),
+			},
+			files,
+			{
+				headers: options.webhookConfig?.headers,
+			},
+		);
+	}
 	const method = options.webhookConfig?.method === 'POST' ? post : get;
 	return await method<SendMessageResponse>(
 		`${options.webhookUrl}`,