Implement health check service and global exception handling

frontend/app/recipes/RecipePreview.tsx

@@ -2,6 +2,7 @@
 
 import { useState, useTransition } from 'react';
 import Link from 'next/link';
+import { parseErrorResponse } from '../../lib/error-handler';
 import type {
   Recipe,
   RecipeInventoryPreview,
@@ -74,14 +75,15 @@ export default function RecipePreview({ recipes }: Props) {
         });
 
         if (!res.ok) {
-          const text = await res.text();
-          throw new Error(text || 'Kunde inte hämta recept-preview.');
+          const errorMessage = await parseErrorResponse(res);
+          throw new Error(errorMessage);
         }
 
         const data: RecipeInventoryPreview = await res.json();
         setPreview(data);
       } catch (err) {
-        setError(err instanceof Error ? err.message : 'Okänt fel');
+        const message = err instanceof Error ? err.message : 'Ett okänt fel inträffade.';
+        setError(message);
       }
     });
   };