Restructure compose mirror: stacks/ grouped by purpose, not by host

Replaces rocky-docker-lxc/, caddy-vm/, monitoring-vm/, and automation/
with a single stacks/ tree grouped by function (identity-and-security,
platform, media, productivity, dev-tools) - 55 stacks total, every one
a real directory in the private repos today.

Resolves all outstanding drift: adds Wazuh (previously entirely
missing), Firefly III and Postiz (never mirrored), the internal-zone
Caddy instance and the Cron Scheduler's separate NocoDB instance
(both previously conflated with their counterparts under one shared
folder); renames Calibre-Web to calibre-web-automated and splits
Kodi-MariaDB into kodi + mariadb-latest to match what the private
repos actually run now; drops the decommissioned NetBox stack.

Also removes automation/iac/old-content/ and
automation/ansible/old-playbooks/ in the same pass - both folders
were entirely stale content describing a superseded architecture
(GitLab instead of Gitea, HAProxy+mTLS SSO instead of the current
Caddy+Authentik setup), now replaced by docs/iac-pipeline.md.

stacks/platform/docker-socket-proxy/docker-compose.yaml

@@ -0,0 +1,23 @@
+services:
+  socket-proxy:
+    image: tecnativa/docker-socket-proxy
+    container_name: socket-proxy
+    restart: always
+    environment:
+      - CONTAINERS=1
+      - IMAGES=0
+      - NETWORKS=0
+      - VOLUMES=0
+      - EVENTS=0
+      - POST=0
+      - DELETE=0
+      - INFO=1
+      - EXEC=0
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+    networks:
+      - docker-proxy-net
+
+networks:
+  docker-proxy-net:
+    external: true