Reorganize project. Add folder for shared code between backend/dashboard. Switch from jest to ava for tests.

backend/src/api/responses.ts

@@ -0,0 +1,25 @@
+import { Response } from "express";
+
+export function unauthorized(res: Response) {
+  res.status(403).json({ error: "Unauthorized" });
+}
+
+export function error(res: Response, message: string, statusCode: number = 500) {
+  res.status(statusCode).json({ error: message });
+}
+
+export function serverError(res: Response, message = "Server error") {
+  error(res, message, 500);
+}
+
+export function clientError(res: Response, message: string) {
+  error(res, message, 400);
+}
+
+export function notFound(res: Response) {
+  res.status(404).json({ error: "Not found" });
+}
+
+export function ok(res: Response) {
+  res.json({ result: "ok" });
+}