feat: add modules/storage export and bundle config files

- Add `./modules/storage` package export pointing to `modules.storage.js`
- Add `modules/*/config.js` to tsup build entries for server-only configs
- Add `@zen/core/modules/storage` to external dependencies in tsup config
- Add `src/modules/modules.storage.js` to the second tsup build target
- Update storage handler to import via `@zen/core/modules/storage` alias
- Rename unused `request` param to `_request` in `handleGetFile`

src/core/api/handlers/storage.js

@@ -6,7 +6,7 @@
 import { validateSession } from '../../../features/auth/lib/session.js';
 import { cookies } from 'next/headers';
 import { getSessionCookieName } from '../../../shared/lib/appConfig.js';
-import { getAllStoragePublicPrefixes } from '../../../../modules/modules.storage.js';
+import { getAllStoragePublicPrefixes } from '@zen/core/modules/storage';
 import { getFile } from '@zen/core/storage';
 
 // Get cookie name from environment or use default
@@ -18,7 +18,7 @@ const COOKIE_NAME = getSessionCookieName();
  * @param {string} fileKey - The file key/path in storage
  * @returns {Promise<Response|Object>} File response or error object
  */
-export async function handleGetFile(request, fileKey) {
+export async function handleGetFile(_request, fileKey) {
   try {
     // Reject any path that contains traversal sequences, empty segments, or
     // absolute path indicators before splitting or passing to the storage backend.