chore: simplify env config

vite.umd.config.js

@@ -0,0 +1,38 @@
+// @ts-check
+import { dirname, resolve } from 'path'
+import { fileURLToPath } from 'url'
+import { defineConfig } from 'vite'
+import cssInjectedByJsPlugin from 'vite-plugin-css-injected-by-js'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = dirname(__filename)
+
+/** @type {import('vite').UserConfig} */
+const config = {
+	// Library build configuration
+	plugins: [cssInjectedByJsPlugin({ relativeCSSInjection: true })],
+	resolve: {
+		alias: {
+			'@': resolve(__dirname, 'src'),
+		},
+	},
+	publicDir: false,
+	esbuild: {
+		keepNames: true,
+	},
+	build: {
+		lib: {
+			entry: resolve(__dirname, 'src/entry.ts'),
+			name: 'PageAgent',
+			fileName: 'page-agent',
+			formats: ['umd'],
+		},
+		outDir: resolve(__dirname, 'dist', 'umd'),
+		cssCodeSplit: true,
+	},
+	define: {
+		'process.env.NODE_ENV': '"production"',
+	},
+}
+
+export default defineConfig(config)