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>

group_vars/all/infrastructure.yml

@@ -0,0 +1,22 @@
+# Infrastructure Configuration
+
+# Docker configuration
+docker:
+  network_name: "lava"
+  stacks_path: "/opt/stacks"
+  hairpin_ip: "172.20.0.5"
+
+# SMTP configuration
+smtp:
+  host: "smtp.resend.com"
+  username: "resend"
+  from_domain: "{{ email_domains.updates }}"
+
+# Network configuration
+network:
+  netcup_ip: "152.53.36.98"
+  docker_host_ip: "100.70.169.99"
+
+# Paths
+paths:
+  stacks: "{{ docker.stacks_path }}"