fix: add TypeScript declarations for @lwrjs/api module

- Added TypeScript declaration file in src/types/lwrjs-api.d.ts
- Added declaration file in node_modules/@types/lwrjs__api/index.d.ts for runtime resolution
- Updated tsconfig.json to include .d.ts files
- Exports specific functions used in site.ts: expDev, setupDev, SitesLocalDevOptions
- Resolves TS7016 module resolution error in CI and local environments

Author: lesya7

src/types/lwrjs-api.d.ts

@@ -0,0 +1,20 @@
+/*
+ * 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 LwrConfig = Record<string, unknown>;
+  export type LwrServer = Record<string, unknown>;
+  export type SitesLocalDevOptions = Record<string, unknown>;
+
+  export function createServer(config: LwrConfig): LwrServer;
+  export function expDev(options: SitesLocalDevOptions): Promise<void>;
+  export function setupDev(options: SitesLocalDevOptions): Promise<void>;
+
+  // Export everything else as unknown to maintain compatibility
+  export const api: unknown;
+  export default api;
+}

tsconfig.json

@@ -6,5 +6,5 @@
     "skipLibCheck": true,
     "baseUrl": "."
   },
-  "include": ["./src/**/*.ts"]
+  "include": ["./src/**/*.ts", "./src/**/*.d.ts"]
 }