feat: add Gotify notification server with iGotify iOS support

Add comprehensive push notification infrastructure with:
- Gotify server for push notifications with admin password configuration
- iGotify Assistant service for iOS notification relay via Apple Push Notifications
- Dual subdomain setup (gotify.* and gotify-assistant.*)
- Proper service dependencies and container communication via hairpinning
- Caddy reverse proxy configuration for both services
- DNS A records for both subdomains
- Added to monitoring services category
- Tested with successful notification delivery

Services accessible at:
- https://gotify.thesatelliteoflove.com (main server)
- https://gotify-assistant.thesatelliteoflove.com (iOS assistant)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

group_vars/docker/services.yml

@@ -7,7 +7,7 @@ service_categories:
   media: ["audiobookshelf", "calibre", "ghost", "pinchflat", "pinry", "hoarder", "manyfold"]
   productivity: ["paperlessngx", "baikal", "syncthing", "mmdl", "heyform", "dawarich", "pingvin"]
   communication: ["gotosocial", "postiz"]
-  monitoring: ["glance", "changedetection", "appriseapi"]
+  monitoring: ["glance", "changedetection", "appriseapi", "gotify"]
 
 # Common service configuration
 services: