Import project configuration: backend/vitest.config.ts

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

backend/vitest.config.ts

@@ -0,0 +1,15 @@
+import { defineConfig } from "vitest/config";
+import path from "path";
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: "node",
+    setupFiles: ["./tests/setup.ts"],
+    include: ["tests/integration/**/*.{test,spec}.ts"],
+    exclude: ["tests/integration/resilience.test.ts"],
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+});