add route matcher to fix /login and /logout routes

Use SvelteKit param matcher to constrain [recipeLang] to only match
'recipes' or 'rezepte', preventing it from catching /login, /logout,
and other non-recipe routes.

src/routes/[recipeLang=recipeLang]/season/[month]/+page.server.ts

@@ -0,0 +1,22 @@
+import type { PageServerLoad } from "./$types";
+import { getUserFavorites, addFavoriteStatusToRecipes } from "$lib/server/favorites";
+
+export const load: PageServerLoad = async ({ fetch, locals, params }) => {
+    const isEnglish = params.recipeLang === 'recipes';
+    const apiBase = isEnglish ? '/api/recipes' : '/api/rezepte';
+
+    const res_season = await fetch(`${apiBase}/items/in_season/` + params.month);
+    const item_season = await res_season.json();
+
+    // Get user favorites and session
+    const [userFavorites, session] = await Promise.all([
+        getUserFavorites(fetch, locals),
+        locals.auth()
+    ]);
+
+    return {
+        month: params.month,
+        season: addFavoriteStatusToRecipes(item_season, userFavorites),
+        session
+    };
+};