feat: add Grocy kitchen ERP service

- Add grocy subdomain to domains.yml
- Create Docker Compose template using LinuxServer image
- Add Ansible task for service deployment
- Configure Caddy reverse proxy with Authentik auth and API bypass
- Add DNS record for grocy subdomain
- Integrate with productivity services category

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

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

group_vars/all/domains.yml

@@ -33,6 +33,7 @@ subdomains:
   gotify: "gotify.{{ primary_domain }}"  # Gotify notifications
   gotify_assistant: "gotify-assistant.{{ primary_domain }}"  # iGotify iOS assistant
   kanboard: "kanboard.{{ primary_domain }}"  # Kanboard project management
+  grocy: "grocy.{{ primary_domain }}"  # Grocy kitchen ERP
 
 # Email domains for notifications
 email_domains: