feat(pwa): Schreib-Aktionen zeigen Offline-Toast statt stillem Fail

Neuer Helper requireOnline(action) prüft vor jedem Schreib-Fetch
den Online-Status. Offline: ein Toast erscheint ("Die Aktion braucht
eine Internet-Verbindung."), Aktion bricht sauber ab. Der Button-
State bleibt unverändert (kein optimistisches Update, das gleich
wieder zurückgedreht werden müsste).

Eingebaut in Rezept-Detail (8 Handler), Register (2), Wunschliste
(2), Admin Domains/Profile/Backup, Home-Dismiss.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/routes/recipes/+page.svelte

@@ -3,6 +3,7 @@
   import { CookingPot, Link, Plus, ChevronDown, Pencil } from 'lucide-svelte';
   import { goto } from '$app/navigation';
   import { alertAction } from '$lib/client/confirm.svelte';
+  import { requireOnline } from '$lib/client/require-online';
   import type { PageData } from './$types';
 
   let { data }: { data: PageData } = $props();
@@ -35,12 +36,14 @@
     e.preventDefault();
     const url = importUrl.trim();
     if (!url) return;
+    if (!requireOnline('Der URL-Import')) return;
     importOpen = false;
     goto(`/preview?url=${encodeURIComponent(url)}`);
   }
 
   async function createBlank() {
     if (creatingBlank) return;
+    if (!requireOnline('Das Anlegen')) return;
     menuOpen = false;
     creatingBlank = true;
     try {

src/routes/recipes/[id]/+page.svelte

@@ -20,6 +20,7 @@
   import { profileStore } from '$lib/client/profile.svelte';
   import { wishlistStore } from '$lib/client/wishlist.svelte';
   import { confirmAction, alertAction } from '$lib/client/confirm.svelte';
+  import { requireOnline } from '$lib/client/require-online';
   import type { CommentRow } from '$lib/server/recipes/actions';
 
   let { data } = $props();
@@ -69,6 +70,7 @@
     ingredients: typeof data.recipe.ingredients;
     steps: typeof data.recipe.steps;
   }) {
+    if (!requireOnline('Das Speichern')) return;
     saving = true;
     try {
       const res = await fetch(`/api/recipes/${data.recipe.id}`, {
@@ -127,6 +129,7 @@
       });
       return;
     }
+    if (!requireOnline('Das Rating')) return;
     await fetch(`/api/recipes/${data.recipe.id}/rating`, {
       method: 'PUT',
       headers: { 'content-type': 'application/json' },
@@ -145,6 +148,7 @@
       });
       return;
     }
+    if (!requireOnline('Das Favorit-Setzen')) return;
     const profileId = profileStore.active.id;
     const wasFav = isFav;
     const method = wasFav ? 'DELETE' : 'PUT';
@@ -167,6 +171,7 @@
       });
       return;
     }
+    if (!requireOnline('Der Kochjournal-Eintrag')) return;
     const res = await fetch(`/api/recipes/${data.recipe.id}/cooked`, {
       method: 'POST',
       headers: { 'content-type': 'application/json' },
@@ -188,6 +193,7 @@
       });
       return;
     }
+    if (!requireOnline('Das Speichern des Kommentars')) return;
     const text = newComment.trim();
     if (!text) return;
     const res = await fetch(`/api/recipes/${data.recipe.id}/comments`, {
@@ -219,6 +225,7 @@
       destructive: true
     });
     if (!ok) return;
+    if (!requireOnline('Das Löschen')) return;
     await fetch(`/api/recipes/${data.recipe.id}`, { method: 'DELETE' });
     goto('/');
   }
@@ -242,6 +249,7 @@
       editingTitle = false;
       return;
     }
+    if (!requireOnline('Das Umbenennen')) return;
     const res = await fetch(`/api/recipes/${data.recipe.id}`, {
       method: 'PATCH',
       headers: { 'content-type': 'application/json' },
@@ -277,6 +285,7 @@
       });
       return;
     }
+    if (!requireOnline('Das Wunschlisten-Setzen')) return;
     const profileId = profileStore.active.id;
     const wasOn = onMyWishlist;
     if (wasOn) {