feat: replace Web Push with ntfy for medication reminders

Single notification path via ntfy HTTP publish for reliable Android delivery;
remove VAPID, push subscriptions, and SW push handlers. PWA settings show
topic subscribe link; humor texts and deep-link actions unchanged.

Co-authored-by: Cursor <cursoragent@cursor.com>

public/lib/pwa.js

@@ -46,23 +46,3 @@ export async function registerPwa() {
     console.error("SW registration failed:", e);
   }
 }
-
-export async function subscribePush(vapidPublicKey) {
-  if (!("PushManager" in window)) throw new Error("Push nicht unterstützt");
-  const reg = await navigator.serviceWorker.ready;
-  let sub = await reg.pushManager.getSubscription();
-  if (!sub) {
-    sub = await reg.pushManager.subscribe({
-      userVisibleOnly: true,
-      applicationServerKey: urlBase64ToUint8Array(vapidPublicKey),
-    });
-  }
-  return sub.toJSON();
-}
-
-function urlBase64ToUint8Array(base64String) {
-  const padding = "=".repeat((4 - (base64String.length % 4)) % 4);
-  const base64 = (base64String + padding).replace(/-/g, "+").replace(/_/g, "/");
-  const raw = atob(base64);
-  return Uint8Array.from([...raw].map((c) => c.charCodeAt(0)));
-}