chore: Add build version as banner to outputted js and css chat files (no-changelog) (#16629)

Co-authored-by: cubic-dev-ai[bot] <191113872+cubic-dev-ai[bot]@users.noreply.github.com>

packages/frontend/@n8n/chat/vite.config.mts

@@ -1,10 +1,11 @@
-import { defineConfig, mergeConfig } from 'vite';
+import { defineConfig, mergeConfig, PluginOption } from 'vite';
 import { resolve } from 'path';
-import { renameSync } from 'fs';
+import { renameSync, writeFileSync, readFileSync } from 'fs';
 import vue from '@vitejs/plugin-vue';
 import icons from 'unplugin-icons/vite';
 import dts from 'vite-plugin-dts';
 import { vitestConfig } from '@n8n/vitest-config/frontend';
+import pkg from './package.json';
 import iconsResolver from 'unplugin-icons/resolver';
 import components from 'unplugin-vue-components/vite';
 
@@ -12,6 +13,8 @@ const includeVue = process.env.INCLUDE_VUE === 'true';
 const srcPath = resolve(__dirname, 'src');
 const packagesDir = resolve(__dirname, '..', '..', '..');
 
+const banner = `/*! Package version @n8n/chat@${pkg.version} */`;
+
 // https://vitejs.dev/config/
 export default mergeConfig(
 	defineConfig({
@@ -49,6 +52,19 @@ export default mergeConfig(
 					}
 				},
 			},
+			{
+				name: 'inject-build-version',
+				closeBundle() {
+					const cssPath = resolve(__dirname, 'dist', 'style.css');
+					try {
+						const cssContent = readFileSync(cssPath, 'utf-8');
+						const updatedCssContent = banner + '\n' + cssContent;
+						writeFileSync(cssPath, updatedCssContent, 'utf-8');
+					} catch (error) {
+						console.error('Failed to inject build version into CSS file:', error);
+					}
+				},
+			},
 		],
 		resolve: {
 			alias: [
@@ -86,6 +102,8 @@ export default mergeConfig(
 				external: includeVue ? [] : ['vue'],
 				output: {
 					exports: 'named',
+					// inject banner on top of all JS files
+					banner,
 					// Provide global variables to use in the UMD build
 					// for externalized deps
 					globals: includeVue