feat: complete variable management implementation and update documentation

- Update remaining Docker Compose templates with centralized variables
- Fix service tag isolation to deploy individual services only
- Update all README files with variable management architecture
- Document variable hierarchy in DEPLOYMENT_LEARNINGS.md
- Add comprehensive variable usage patterns to CLAUDE.md
- Standardize domain references using {{ subdomains.* }} pattern
- Replace hardcoded network names with {{ docker.network_name }}
- Update hairpinning configuration to use variables

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

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

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

@@ -14,7 +14,7 @@ services:
     labels:
       glance.name: Paperless NGX
       glance.icon: si:paperlessngx
-      glance.url: https://papers.thesatelliteoflove.com/
+      glance.url: https://{{ subdomains.paper }}/
       glance.description: Document server
       glance.id: paperlessngx
     depends_on:
@@ -28,7 +28,7 @@ services:
       - ./consume:/usr/src/paperless/consume
     env_file: docker-compose.env
     extra_hosts:
-      - 'auth.thesatelliteoflove.com:172.20.0.5'
+      - '{{ subdomains.auth }}:{{ docker.hairpin_ip }}'
     environment:
       PAPERLESS_REDIS: redis://broker:6379
       PAPERLESS_TIKA_ENABLED: 1
@@ -65,4 +65,4 @@ volumes:
 networks:
   default:
     external: true
-    name: lava
+    name: {{ docker.network_name }}