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>

tools/gen_vapid.py

@@ -1,19 +0,0 @@
-#!/usr/bin/env python3
-"""Generate VAPID key pair for Web Push. Run: python tools/gen_vapid.py"""
-from __future__ import annotations
-
-from py_vapid import Vapid
-
-
-def main() -> None:
-    vapid = Vapid()
-    vapid.generate_keys()
-    private = vapid.private_pem.decode().strip()
-    public = vapid.public_key.decode().strip() if hasattr(vapid.public_key, "decode") else str(vapid.public_key)
-    print("Add these to your .env:\n")
-    print(f"VAPID_PRIVATE_KEY={private}")
-    print(f"VAPID_PUBLIC_KEY={public}")
-
-
-if __name__ == "__main__":
-    main()