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>

bootstrap.yml

@@ -3,11 +3,8 @@
   become: true
   vars:
     created_username: phil
-  vars_prompt:
-    - name: tailscale_key
-      prompt: Enter the tailscale key
   roles:
     - bootstrap
     - role: artis3n.tailscale
       vars:
-        tailscale_authkey: "{{ tailscale_key }}"
+        tailscale_authkey: "{{ vault_infrastructure.tailscale_key }}"