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were entirely stale content describing a superseded architecture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/productivity/joplin/docker-compose.yaml

@@ -0,0 +1,56 @@
+services:
+  joplin-db:
+    image: postgres:latest
+    container_name: joplin-db
+    volumes:
+      - /path/to/joplin:/var/lib/postgresql
+    ports:
+      - "${POSTGRES_PORT}:5432"
+    restart: unless-stopped
+    environment:
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
+      - POSTGRES_USER=${POSTGRES_USER}
+      - POSTGRES_DB=${POSTGRES_DB}
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER} -d ${POSTGRES_DB}"]
+      interval: 5s
+      timeout: 5s
+      retries: 10
+      start_period: 15s
+    networks:
+      - joplin-net
+
+  joplin:
+    image: joplin/server:latest
+    container_name: joplin-server
+    depends_on:
+      - joplin-db
+    ports:
+      - "${HTTP_PORT}:22300"
+    restart: unless-stopped
+    environment:
+      - APP_PORT=${HTTP_PORT}
+      - APP_BASE_URL=${APP_BASE_URL}
+      - DB_CLIENT=pg
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
+      - POSTGRES_DATABASE=${POSTGRES_DB}
+      - POSTGRES_USER=${POSTGRES_USER}
+      - POSTGRES_PORT=${POSTGRES_PORT}
+      - POSTGRES_HOST=joplin-db
+      - MAILER_ENABLED=1
+      - MAILER_HOST=${MAILER_HOST}
+      - MAILER_PORT=${MAILER_PORT}
+      - MAILER_SECURITY=${MAILER_SECURITY}
+      - MAILER_AUTH_USER=${MAILER_AUTH_USER}
+      - MAILER_AUTH_PASSWORD=${MAILER_AUTH_PASSWORD}
+      - MAILER_NOREPLY_NAME=${MAILER_NOREPLY_NAME}
+      - MAILER_NOREPLY_EMAIL=${MAILER_NOREPLY_EMAIL}
+      - APP_ADMIN_EMAIL=${APP_ADMIN_EMAIL}
+      - APP_ADMIN_PASSWORD=${APP_ADMIN_PASSWORD}
+      - APP_ADMIN_NAME=${APP_ADMIN_NAME}
+    networks:
+      - joplin-net
+
+networks:
+  joplin-net:
+    external: true