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were entirely stale content describing a superseded architecture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/media/jellyfin/docker-compose.yaml

@@ -0,0 +1,32 @@
+services:
+  jellyfin:
+    image: jellyfin/jellyfin:latest
+    container_name: jellyfin
+    environment:
+      - PUID=${PUID}
+      - PGID=${PGID}
+      - TZ=${TZ}
+    volumes:
+      - /path/to/jellyfin/config:/config
+      - /path/to/jellyfin/cache:/cache
+      - /path/to/media:/data
+      - /path/to/transcodes/jellyfin:/transcodes
+    ports:
+      - ${HTTP_PORT}:8096
+    restart: unless-stopped
+    healthcheck:
+      test:
+        [
+          "CMD-SHELL",
+          "curl -fsS http://localhost:8096/health | grep -q Healthy",
+        ]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 60s
+    networks:
+      - media-net
+
+networks:
+  media-net:
+    external: true