test: add TypeScript declaration file from nut-test

- Added src/lwrjs-api.d.ts with type declarations for @lwrjs/api
- Declares SitesLocalDevOptions type and expDev/setupDev functions
- Testing if this TypeScript declaration file causes @lwrjs/api module resolution issues in CI
- This is the most likely culprit for the TS7016 error

Author: lesya7

src/lwrjs-api.d.ts

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2025, salesforce.com, inc.
+ * All rights reserved.
+ * Licensed under the BSD 3-Clause license.
+ * For full license text, see LICENSE.txt file in the repo root or https://opensource.org/licenses/BSD-3-Clause
+ */
+
+declare module '@lwrjs/api' {
+  export type SitesLocalDevOptions = {
+    [key: string]: unknown;
+    sfCLI?: boolean;
+    authToken?: string;
+    open?: boolean;
+    port?: number;
+    logLevel?: string;
+    mode?: string;
+    siteZip?: string;
+    siteDir?: string;
+  };
+
+  export function expDev(options: SitesLocalDevOptions): Promise<void>;
+  export function setupDev(options: SitesLocalDevOptions): Promise<void>;
+}