chore: update test webServer to use preview mode

frontend/playwright.config.ts

@@ -60,7 +60,8 @@ export default defineConfig({
 
   /* Run your local dev server before starting the tests */
   webServer: {
-    command: "npm run dev -- --mode e2e",
+    // NOTE: using npm here for docker compat mainly
+    command: "npm run build -- --mode e2e && npm run preview -- --mode e2e",
     url: getBaseUrl(
       process.env.SSL_ENABLED === "true",
       process.env.FRONTEND_DOMAIN,

frontend/vite.config.ts

@@ -46,5 +46,10 @@ export default defineConfig(({ mode }) => {
       host: env.FRONTEND_DOMAIN,
       https: isSslEnabled ? sslCerts : undefined,
     },
+    preview: {
+      port: Number(env.FRONTEND_PORT),
+      host: env.FRONTEND_DOMAIN,
+      https: isSslEnabled ? sslCerts : undefined,
+    },
   };
 });