feat(security): opt-in local CrowdSec LAPI bouncer on the Docker engine

docs/operations/docker-installation.md

@@ -85,6 +85,22 @@ The direct template intentionally records the CDN/edge socket address when place
 
 `pnpm test:integration` additionally starts disposable Nginx containers from the actual templates, supplies a temporary test certificate, and sends real HTTPS requests with forged identity headers. It checks direct-mode replacement even with an inherited real-IP rule, rejection of untrusted peers, and acceptance through an explicitly trusted peer. This requires Docker Engine and the OpenSSL CLI and does not read deployment credentials. The templates must still pass `nginx -t` on the intended host after its hostname/certificate substitution, then the listener and trusted-header checks above; the disposable fixture cannot certify that host or its firewall.
 
+## Opt-in: CrowdSec on the same Docker host
+
+A self-contained CrowdSec engine ships in `deployment/crowdsec`. It reads the host Nginx access log, runs `crowdsecurity/crowdsec:1.8.1` in its own Compose project and exposes LAPI only on `127.0.0.1:18080`. No reverse-proxy, Traefik, Cloudflare or firewall configuration is changed.
+
+```sh
+bash cms security
+```
+
+The command generates `CROWDSEC_LAPI_API_KEY`, writes the CrowdSec flags into `.env`, starts the engine and registers the `cms` bouncer. The anti-DDoS gate then consults the local LAPI per client IP (short-cached) and blocks `ban`/`captcha` decisions before its own rate buckets. `bash cms security status` reports engine state and `bash cms security disable` stops the engine and flips the toggle off.
+
+The engine does not enroll into the CrowdSec Central API (`DISABLE_ONLINE_API=true`): detection stays local. The app still has its separate opt-in traffic-sharing channel via `CROWDSEC_REPORT_ENABLED`. Change `CROWDSEC_LAPI_PORT` and `CROWDSEC_LAPI_URL` together when `18080` is already in use. `CROWDSEC_NGINX_LOG_DIR` overrides the log directory the engine acquires.
+
+This bouncer is application-layer: it sheds known-bad IPs at the CMS process and only for traffic that reaches the Next.js proxy. It does not drop traffic before the origin, does not protect other host ports/services, and depends on the client IP being trustworthy at the ingress. Keep the upstream protections (Cloudflare IP rules, proxy rate limits) for defense before the origin.
+
+The running CMS loads the new env values on its next restart or deployment. For a CI-managed `epicnext-cms-app`, the next deploy (which sources `.env`) applies them; for a clone, `bash cms update --skip-pull` restarts it. `.env` now holds the LAPI key — keep its permissions restrictive.
+
 ## Routine and selected-release updates
 
 ```sh