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were entirely stale content describing a superseded architecture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

@@ -0,0 +1,48 @@
+services:
+  gitea:
+    image: gitea/gitea:latest
+    container_name: gitea
+    environment:
+      - PUID=${PUID}
+      - PGID=${PGID}
+      - TZ=${TZ}
+      - GITEA__database__DB_TYPE=postgres
+      - GITEA__database__HOST=gitea-db
+      - GITEA__database__PORT=5432
+      - GITEA__database__NAME=${POSTGRES_DB}
+      - GITEA__database__USER=${POSTGRES_USER}
+      - GITEA__database__PASSWD=${POSTGRES_PASSWORD}
+      - ROOT_URL=${GITEA_ROOT_URL}
+      - DOMAIN=${GITEA_DOMAIN}
+      - GITEA__migrations__ALLOW_LOCALNETWORKS=true
+    restart: always
+    volumes:
+      - /path/to/gitea:/data
+      - /etc/timezone:/etc/timezone:ro
+      - /etc/localtime:/etc/localtime:ro
+    ports:
+      - "${HTTP_PORT}:3000"
+      - "${SSH_PORT}:22"
+    depends_on:
+      - gitea-db
+    security_opt:
+      - no-new-privileges:true
+    networks:
+      - gitea-net
+
+  gitea-db:
+    image: postgres:latest
+    container_name: gitea-db
+    restart: always
+    environment:
+      - POSTGRES_USER=${POSTGRES_USER}
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}
+      - POSTGRES_DB=${POSTGRES_DB}
+    volumes:
+      - /path/to/gitea/postgres:/var/lib/postgresql
+    networks:
+      - gitea-net
+
+networks:
+  gitea-net:
+    external: true