Add logout route

src/node/routes/logout.ts

@@ -0,0 +1,17 @@
+import { Router } from "express"
+import { getCookieDomain, redirect } from "../http"
+import { Cookie } from "./login"
+
+export const router = Router()
+
+router.get("/", async (req, res) => {
+  // Must use the *identical* properties used to set the cookie.
+  res.clearCookie(Cookie.Key, {
+    domain: getCookieDomain(req.headers.host || "", req.args["proxy-domain"]),
+    path: req.body.base || "/",
+    sameSite: "lax",
+  })
+
+  const to = (typeof req.query.to === "string" && req.query.to) || "/"
+  return redirect(req, res, to, { to: undefined, base: undefined })
+})