fix Darwin canonical test fixtures

backend/test/app.test.ts

@@ -1,4 +1,16 @@
-import { describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it } from "vitest";
+import { mkdtempSync, realpathSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { loadConfig } from "../src/config.js";
 import { buildApp } from "../src/app.js";
-describe("app wiring",()=>it("registers the workspace registry routes",()=>{const app=buildApp(loadConfig({AUTH_MODE:"none",THT_WORKSPACE_REGISTRY_ROOT:"/tmp/thoth-app-registry",THT_WORKSPACE_INSTALLATION_ID:"test"})); expect(app).toBeDefined();}));
+
+const roots: string[] = [];
+afterEach(() => { for (const root of roots.splice(0)) rmSync(root, { recursive: true, force: true }); });
+
+describe("app wiring", () => it("registers the workspace registry routes", () => {
+  const root = realpathSync(mkdtempSync(join(process.platform === "darwin" ? "/private/tmp" : tmpdir(), "thoth-app-registry-")));
+  roots.push(root);
+  const app = buildApp(loadConfig({ AUTH_MODE: "none", THT_WORKSPACE_REGISTRY_ROOT: root, THT_WORKSPACE_INSTALLATION_ID: "test" }));
+  expect(app).toBeDefined();
+}));