chore: add server.js for Plesk Passenger startup

Required by Phusion Passenger on Plesk production.
Must not be deleted by git clean or deploys will 500.

server.js

@@ -0,0 +1,17 @@
+const { createServer } = require("http")
+const { parse } = require("url")
+const next = require("next")
+
+const port = parseInt(process.env.PORT || "3000", 10)
+const app = next({ dev: false })
+const handle = app.getRequestHandler()
+
+app.prepare().then(() => {
+  createServer((req, res) => {
+    const parsedUrl = parse(req.url, true)
+    handle(req, res, parsedUrl)
+  }).listen(port, "0.0.0.0", (err) => {
+    if (err) throw err
+    console.log("Next.js server ready on http://0.0.0.0:" + port)
+  })
+})