fix(frontend): Remove ES6 exports from api.ts

Remove ES6 export statement from api.ts that was causing CommonJS
compilation in browsers, breaking window.api initialization.

Issue: TypeScript compiled 'export { ... }' to CommonJS format
(exports.apiGet = ...), which browsers don't support.

Fix: Remove export statement, rely on existing window.api assignment.
This produces browser-compatible JavaScript.

Before: export { getAuthHeader, apiGet, ... } → CommonJS exports
After: (window as any).api = { ... } → browser global

Resolves: 'Uncaught ReferenceError: exports is not defined'
Resolves: 'Uncaught TypeError: window.api is undefined'

web/src/api.ts

@@ -87,15 +87,3 @@ function handleError(error: unknown, context: string): void {
     handleVoidResponse,
     handleError
 };
-
-export {
-    getAuthHeader,
-    apiGet,
-    apiPost,
-    apiPut,
-    apiDelete,
-    apiPatch,
-    handleResponse,
-    handleVoidResponse,
-    handleError
-};