next.js example (#694)

* next.js guide

* better

* shadcn

* fixes

* fix: correct screenshot test assertion to check path instead of base64

The daemon returns { path: savePath } for screenshot commands, not base64.

* fix: cross-platform Chrome detection and gitignore hardening

- Replace hardcoded macOS Chrome path with findLocalChrome() that
  searches common paths on macOS, Linux, and WSL, with a clear error
  message when no Chrome is found.
- Add .env and .env*.local to .gitignore to prevent accidental
  secret commits.

* fix: correct Vercel deploy button repo URL to vercel-labs/agent-browser

* clean up

* demo

* next page

---------

Co-authored-by: ctate <366502+ctate@users.noreply.github.com>

README.md

@@ -713,7 +713,40 @@ agent-browser --executable-path /path/to/chromium open example.com
 AGENT_BROWSER_EXECUTABLE_PATH=/path/to/chromium agent-browser open example.com
 ```
 
-### Serverless Example (Vercel/AWS Lambda)
+### Serverless (Vercel)
+
+Two patterns for using agent-browser from Next.js server actions on Vercel:
+
+**Vercel Sandbox** -- run agent-browser + Chrome in an ephemeral microVM. No external server needed:
+
+```typescript
+import { Sandbox } from "@vercel/sandbox";
+
+const sandbox = await Sandbox.create({ runtime: "node24" });
+await sandbox.runCommand("agent-browser", ["open", "https://example.com"]);
+const result = await sandbox.runCommand("agent-browser", ["screenshot", "--json"]);
+await sandbox.stop();
+```
+
+**External API server** -- host agent-browser on a server, call it from Vercel via HTTP:
+
+```typescript
+const res = await fetch(`${process.env.AGENT_BROWSER_API_URL}/api/run`, {
+  method: "POST",
+  headers: { "Content-Type": "application/json" },
+  body: JSON.stringify({
+    commands: [
+      { action: "launch", headless: true },
+      { action: "navigate", url: "https://example.com" },
+      { action: "screenshot" },
+    ],
+  }),
+});
+```
+
+See the [demo app](examples/demo/) for a visual demo of agent-browser's core capabilities across different compute environments.
+
+### Serverless (AWS Lambda)
 
 ```typescript
 import chromium from '@sparticuz/chromium';