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>

pyproject.toml

@@ -1,7 +1,7 @@
 [project]
 name = "takeyourmeds"
 version = "1.0.0"
-description = "Medikamenten-PWA mit Push-Erinnerungen und sarkastischem Humor"
+description = "Medikamenten-PWA mit ntfy-Erinnerungen und sarkastischem Humor"
 requires-python = ">=3.11"
 dependencies = [
   "fastapi>=0.115",
@@ -12,7 +12,6 @@ dependencies = [
   "pyjwt>=2.9",
   "pyyaml>=6.0",
   "httpx>=0.27",
-  "pywebpush>=2.0",
   "apscheduler>=3.10",
 ]