Refactor project to transition from Rust backend to Node.js with Fastify; update Dockerfile and Docker configurations for new build process; enhance local development instructions in CONTRIBUTING.md; implement health checks in Docker Compose; update pnpm-lock.yaml with new dependencies for API and shared packages; revise README.md to reflect new stack and development setup.

apps/api/src/plugins/error-handler.ts

@@ -0,0 +1,18 @@
+import type { FastifyInstance } from "fastify";
+import fp from "fastify-plugin";
+import { AppError, errorBody, toAppError } from "../errors.js";
+
+async function errorHandlerPlugin(app: FastifyInstance) {
+  app.setErrorHandler((err, _request, reply) => {
+    if (reply.sent) return;
+
+    const appErr =
+      err.statusCode === 401
+        ? AppError.unauthorized()
+        : toAppError(err);
+
+    reply.status(appErr.statusCode).send(errorBody(appErr));
+  });
+}
+
+export default fp(errorHandlerPlugin, { name: "error-handler" });