Add some stub user stuff

express/user.ts

@@ -181,8 +181,19 @@ export class User {
     toJSON(): UserData {
         return { ...this.data };
     }
+
+    toString(): string {
+        return `User(id ${this.id})`;
+    }
 }
 
 // For representing "no user" in contexts where user is optional
 export const AnonymousUser = Symbol("AnonymousUser");
+
+export const anonymousUser = User.create("anonymous@example.com", {
+    id: "-1",
+    displayName: "Anonymous User",
+    // FIXME: set createdAt and updatedAt to start of epoch
+});
+
 export type MaybeUser = User | typeof AnonymousUser;