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/all/domains.yml

@@ -29,6 +29,8 @@ subdomains:
   appriseapi: "appriseapi.{{ primary_domain }}"
   dockge: "dockge.{{ primary_domain }}"
   code: "code.{{ primary_domain }}"  # Code Server
+  gotify: "gotify.{{ primary_domain }}"  # Gotify notifications
+  gotify_assistant: "gotify-assistant.{{ primary_domain }}"  # iGotify iOS assistant
 
 # Email domains for notifications
 email_domains: