add pdf viewer

backend/routes/api.php

@@ -12,6 +12,10 @@ Route::get('/me', [AuthController::class, 'me'])
     ->middleware(AuthMiddleware::class);
 Route::get('/sets', [SetController::class, 'index']);
 Route::get('/elements/{id}', [ElementController::class, 'show']);
+Route::get('/element-pdfs/{folder}/{fileName}', [
+    ElementController::class,
+    'showPdf',
+]);
 Route::post('/elements/{parentId}/children', [
     ElementController::class,
     'createChild',