fix(pwa): fail offline mutations fast instead of pausing + silent write loss

Mutations ran in TanStack's default 'online' network mode, which PAUSES a
write fired offline: isPending stays true forever, onError never fires,
and the paused mutation is dropped on reload — a health entry vanishes
with no 'not saved' signal. Switch mutations to 'always' network mode so
an offline write rejects immediately and the form surfaces an honest
failure, and add a global OfflineMutationToaster backstop for call sites
without their own onError. Correct the offline banner copy, which promised
changes would auto-save.

messages/de.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Zurück zum Dashboard"
   },
   "offlineBanner": {
-    "message": "Keine Verbindung — Änderungen werden gespeichert, sobald du wieder online bist.",
+    "message": "Keine Verbindung — Änderungen können erst gespeichert werden, wenn du wieder online bist.",
+    "saveFailed": "Speichern fehlgeschlagen — du bist offline. Bitte versuche es erneut, sobald du wieder online bist.",
     "showingCached": "Zeigt deine zuletzt synchronisierten Daten."
   },
   "demoBanner": {

messages/en.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Back to dashboard"
   },
   "offlineBanner": {
-    "message": "No connection — your changes will save once you're back online.",
+    "message": "No connection — changes can't be saved until you're back online.",
+    "saveFailed": "Couldn't save — you're offline. Please try again once you're back online.",
     "showingCached": "Showing your last synced data."
   },
   "demoBanner": {

messages/es.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Volver al panel"
   },
   "offlineBanner": {
-    "message": "Sin conexión — tus cambios se guardarán cuando vuelvas a estar en línea.",
+    "message": "Sin conexión — los cambios no se pueden guardar hasta que vuelvas a estar en línea.",
+    "saveFailed": "No se pudo guardar — estás sin conexión. Inténtalo de nuevo cuando vuelvas a estar en línea.",
     "showingCached": "Mostrando tus últimos datos sincronizados."
   },
   "demoBanner": {

messages/fr.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Retour au tableau de bord"
   },
   "offlineBanner": {
-    "message": "Pas de connexion — tes modifications seront enregistrées dès que tu seras de nouveau en ligne.",
+    "message": "Pas de connexion — les modifications ne peuvent pas être enregistrées tant que tu n'es pas de nouveau en ligne.",
+    "saveFailed": "Enregistrement impossible — tu es hors ligne. Réessaie une fois de nouveau en ligne.",
     "showingCached": "Affichage de tes dernières données synchronisées."
   },
   "demoBanner": {

messages/it.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Torna alla dashboard"
   },
   "offlineBanner": {
-    "message": "Nessuna connessione — le tue modifiche verranno salvate appena torni online.",
+    "message": "Nessuna connessione — le modifiche non possono essere salvate finché non torni online.",
+    "saveFailed": "Impossibile salvare — sei offline. Riprova quando torni online.",
     "showingCached": "Vengono mostrati i tuoi ultimi dati sincronizzati."
   },
   "demoBanner": {

messages/pl.json

@@ -210,7 +210,8 @@
     "backToDashboard": "Powrót do panelu"
   },
   "offlineBanner": {
-    "message": "Brak połączenia — twoje zmiany zostaną zapisane, gdy ponownie pojawisz się online.",
+    "message": "Brak połączenia — zmian nie można zapisać, dopóki nie wrócisz online.",
+    "saveFailed": "Nie udało się zapisać — jesteś offline. Spróbuj ponownie, gdy wrócisz online.",
     "showingCached": "Wyświetlane są ostatnio zsynchronizowane dane."
   },
   "demoBanner": {