Initialise repository structure and placeholder files. Generic functionality works i guess, need to come up with a better solution for compose templates

roles/docker_app/README.md

@@ -0,0 +1,10 @@
+# docker_app
+
+Shared implementation role for single-container Docker Compose applications.
+Application roles set `docker_app_*` variables and include this role.
+
+It supports direct host-port publishing with UFW rules or Traefik routing via
+labels and a shared Docker network.
+
+Tags: `docker_app`, `docker`, `config`, `compose`, `firewall`.
+