Add Vitest configuration for testing environment setup

web/server/vitest.config.js

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vitest/config';
+import os from 'os';
+import path from 'path';
+
+export default defineConfig({
+  test: {
+    env: {
+      DB_PATH: path.join(os.tmpdir(), `inv-test-${process.pid}.db`),
+    },
+  },
+});