Add some missing methods.

app/Api/V2/Controllers/Model/Budget/ShowController.php

@@ -28,6 +28,7 @@ use FireflyIII\Api\V2\Controllers\Controller;
 use FireflyIII\Api\V2\Request\Generic\DateRequest;
 use FireflyIII\Models\Budget;
 use FireflyIII\Repositories\Budget\BudgetRepositoryInterface;
+use FireflyIII\Transformers\V2\BudgetTransformer;
 use Illuminate\Http\JsonResponse;
 
 /**
@@ -50,6 +51,20 @@ class ShowController extends Controller
         );
     }
 
+    /**
+     * Show a budget.
+     */
+    public function show(Budget $budget): JsonResponse
+    {
+        $transformer = new BudgetTransformer();
+        $transformer->setParameters($this->parameters);
+
+        return response()
+            ->api($this->jsonApiObject('budgets', $budget, $transformer))
+            ->header('Content-Type', self::CONTENT_TYPE)
+            ;
+    }
+
     /**
      * 2023-10-29 removed the cerSum reference, not sure where this is used atm
      * so removed from api.php. Also applies to "spent" method.