perf: drop redundant JSON.parse(JSON.stringify()) in recipe API

Every recipe list endpoint wrapped its result in
`JSON.parse(JSON.stringify(...))` before handing it to `json()`, which
then serialises again — a full extra stringify+parse cycle per response.
`lean()` already returns plain objects and ObjectIds/Dates serialise
correctly through `json()`'s single `JSON.stringify`, so the extra round
trip was pure waste.

Removed from the 9 output-side call sites (all_brief, category,
category/[cat], tag, tag/[tag], icon, icon/[icon], in_season/[month],
search, favorites/recipes, offline-db, translate/untranslated).
Kept the two deep-clone-before-mutation usages in items/[name] and
json-ld/[name] — those are load-bearing.

Shuffle stays server-side: moving it to the client would need a hero
preload + hydration rework that's bigger than a perf tweak.

src/routes/api/[recipeLang=recipeLang]/favorites/recipes/+server.ts

@@ -65,10 +65,10 @@ export const GET: RequestHandler = async ({ params, locals }) => {
         germanShortName: recipe.short_name,
         translationStatus: t?.translationStatus
       }});
-      return json(JSON.parse(JSON.stringify(englishRecipes)));
+      return json(englishRecipes);
     }
 
-    return json(JSON.parse(JSON.stringify(recipes)));
+    return json(recipes);
   } catch (e) {
     throw error(500, 'Failed to fetch favorite recipes');
   }

src/routes/api/[recipeLang=recipeLang]/items/all_brief/+server.ts

@@ -11,5 +11,5 @@ export const GET: RequestHandler = async ({ params }) => {
   const dbRecipes = await Recipe.find(approvalFilter, projection).lean();
   const recipes = dbRecipes.map(r => toBrief(r, params.recipeLang!));
 
-  return json(JSON.parse(JSON.stringify(rand_array(recipes))));
+  return json(rand_array(recipes));
 };

src/routes/api/[recipeLang=recipeLang]/items/category/+server.ts

@@ -10,5 +10,5 @@ export const GET: RequestHandler = async ({ params }) => {
   const field = `${prefix}category`;
   const categories = await Recipe.distinct(field, approvalFilter).lean();
 
-  return json(JSON.parse(JSON.stringify(categories)));
+  return json(categories);
 };

src/routes/api/[recipeLang=recipeLang]/items/category/[category]/+server.ts

@@ -14,5 +14,5 @@ export const GET: RequestHandler = async ({ params }) => {
   ).lean();
 
   const recipes = rand_array(dbRecipes.map(r => toBrief(r, params.recipeLang!)));
-  return json(JSON.parse(JSON.stringify(recipes)));
+  return json(recipes);
 };

src/routes/api/[recipeLang=recipeLang]/items/icon/+server.ts

@@ -5,8 +5,7 @@ import type {BriefRecipeType} from '$types/types';
 
 export const GET: RequestHandler = async ({params}) => {
   await dbConnect();
-  let icons = (await Recipe.distinct('icon').lean());
+  const icons = await Recipe.distinct('icon').lean();
 
-  icons = JSON.parse(JSON.stringify(icons));
   return json(icons);
 };

src/routes/api/[recipeLang=recipeLang]/items/icon/[icon]/+server.ts

@@ -14,5 +14,5 @@ export const GET: RequestHandler = async ({ params }) => {
   ).lean();
 
   const recipes = rand_array(dbRecipes.map(r => toBrief(r, params.recipeLang!)));
-  return json(JSON.parse(JSON.stringify(recipes)));
+  return json(recipes);
 };

src/routes/api/[recipeLang=recipeLang]/items/in_season/[month]/+server.ts

@@ -14,5 +14,5 @@ export const GET: RequestHandler = async ({ params }) => {
   ).lean();
   const recipes = dbRecipes.map(r => toBrief(r, params.recipeLang!));
 
-  return json(JSON.parse(JSON.stringify(rand_array(recipes))));
+  return json(rand_array(recipes));
 };

src/routes/api/[recipeLang=recipeLang]/items/tag/+server.ts

@@ -15,9 +15,9 @@ export const GET: RequestHandler = async ({ params }) => {
         recipe.translations.en.tags.forEach((tag: string) => tagsSet.add(tag));
       }
     });
-    return json(JSON.parse(JSON.stringify(Array.from(tagsSet).sort())));
+    return json(Array.from(tagsSet).sort());
   }
 
   const tags = await Recipe.distinct('tags').lean();
-  return json(JSON.parse(JSON.stringify(tags)));
+  return json(tags);
 };

src/routes/api/[recipeLang=recipeLang]/items/tag/[tag]/+server.ts

@@ -14,5 +14,5 @@ export const GET: RequestHandler = async ({ params }) => {
   ).lean();
   const recipes = dbRecipes.map(r => toBrief(r, params.recipeLang!));
 
-  return json(JSON.parse(JSON.stringify(rand_array(recipes))));
+  return json(rand_array(recipes));
 };

src/routes/api/[recipeLang=recipeLang]/offline-db/+server.ts

@@ -72,8 +72,8 @@ export const GET: RequestHandler = async () => {
 	});
 
 	return json({
-		brief: JSON.parse(JSON.stringify(briefRecipes)),
-		full: JSON.parse(JSON.stringify(processedFullRecipes)),
+		brief: briefRecipes,
+		full: processedFullRecipes,
 		syncedAt: new Date().toISOString()
 	});
 };

src/routes/api/[recipeLang=recipeLang]/search/+server.ts

@@ -71,7 +71,7 @@ export const GET: RequestHandler = async ({ url, params, locals }) => {
       });
     }
 
-    return json(JSON.parse(JSON.stringify(recipes)));
+    return json(recipes);
   } catch (e) {
     return json({ error: 'Search failed' }, { status: 500 });
   }

src/routes/api/[recipeLang=recipeLang]/translate/untranslated/+server.ts

@@ -40,7 +40,7 @@ export const GET: RequestHandler = async ({ locals }) => {
 			translationStatus: recipe.translations?.en?.translationStatus || undefined
 		}));
 
-		return json(JSON.parse(JSON.stringify(result)));
+		return json(result);
 	} catch (e) {
 		console.error('Error fetching untranslated recipes:', e);
 		throw error(500, 'Fehler beim Laden der unübersetzten Rezepte');