feat(recipes): return fail(422) when all ingredients filter to empty

Prevents a silent 400 from the backend when the user submits a form
where every ingredient row has quantity <= 0 or blank name.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/(app)/recipes/[id]/edit/+page.server.ts

@@ -67,6 +67,13 @@ export const actions: Actions = {
 			return fail(400, { error: 'Ungültige Formulardaten' });
 		}
 
+		const filteredIngredients = (
+			parsedIngredients as { name: string; quantity: string; unit: string }[]
+		).filter((ing) => ing.name?.trim() && Number(ing.quantity) > 0);
+
+		if (!filteredIngredients.length)
+			return fail(422, { error: 'Mindestens eine gültige Zutat ist erforderlich' });
+
 		const api = apiClient(fetch);
 		const { error: apiError } = await api.PUT('/v1/recipes/{id}', {
 			params: { path: { id: params.id } },
@@ -76,14 +83,12 @@ export const actions: Actions = {
 				cookTimeMin: cookTimeMin ? Number(cookTimeMin) || null : null,
 				effort,
 				heroImageUrl,
-				ingredients: (parsedIngredients as { name: string; quantity: string; unit: string }[])
-					.filter((ing) => ing.name?.trim() && Number(ing.quantity) > 0)
-					.map((ing, i) => ({
-						newIngredientName: ing.name.trim(),
-						quantity: Number(ing.quantity),
-						unit: ing.unit || '',
-						sortOrder: i
-					})),
+				ingredients: filteredIngredients.map((ing, i) => ({
+					newIngredientName: ing.name.trim(),
+					quantity: Number(ing.quantity),
+					unit: ing.unit || '',
+					sortOrder: i
+				})),
 				steps: (parsedSteps as string[])
 					.filter((s) => s?.trim())
 					.map((s, i) => ({ stepNumber: i + 1, instruction: s.trim() })),