feat: implement comprehensive variable management system

- Create standardized group_vars directory structure
- Add domains.yml with centralized subdomain mappings
- Add infrastructure.yml with network, SMTP, and path config
- Reorganize vault.yml secrets by service with consistent naming
- Update 15+ Docker compose templates to use new variable structure
- Simplify playbook commands by removing --extra-vars requirement
- Replace hardcoded domains/IPs with template variables
- Standardize secret references across all services

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

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

roles/docker/templates/calibre-compose.yml.j2

@@ -16,7 +16,7 @@ services:
     labels:
       glance.name: Calibre
       glance.icon: si:calibreweb
-      glance.url: https://books.thesatelliteoflove.com/
+      glance.url: https://{{ subdomains.books }}/
       glance.description: Book server
 volumes:
   config:
@@ -26,4 +26,4 @@ volumes:
 networks:
   default:
     external: true
-    name: lava
+    name: {{ docker.network_name }}