Config tweaks for docker

- Remove `$` interpolation for env
- Allow puppeteer to work headless in docker, headful with npx

src/puppeteer/index.ts

@@ -108,7 +108,9 @@ const screenshots = new Map<string, string>();
 
 async function ensureBrowser() {
   if (!browser) {
-    browser = await puppeteer.launch({ headless: true, args: ["--no-sandbox"] });
+    const npx_args = { headless: false }
+    const docker_args = { headless: true, args: ["--no-sandbox", "--single-process", "--no-zygote"] }
+    browser = await puppeteer.launch(process.env.DOCKER_CONTAINER ? docker_args : npx_args);
     const pages = await browser.pages();
     page = pages[0];