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/conduit-compose.yml.j2

@@ -7,10 +7,10 @@ services:
         labels:
           glance.name: Conduit
           glance.icon: si:matrix
-          glance.url: https://chat.thesatelliteoflove.com/
+          glance.url: https://{{ subdomains.chat }}/
           glance.description: Matrix server
         environment:
-            CONDUIT_SERVER_NAME: chat.thesatelliteoflove.com # EDIT THIS
+            CONDUIT_SERVER_NAME: {{ subdomains.chat }} # EDIT THIS
             CONDUIT_DATABASE_PATH: /var/lib/matrix-conduit/
             CONDUIT_DATABASE_BACKEND: rocksdb
             CONDUIT_PORT: 6167
@@ -43,4 +43,4 @@ volumes:
 networks:
   default:
     external: true
-    name: lava
+    name: {{ docker.network_name }}