Add CrowdSec setup readme for Docker-based deployment

Documents API key generation, storage, bouncer registration,
and useful cscli commands.

https://claude.ai/code/session_01PwAXuaoJx7qD5FhVLsn7Sn

services/crowdsec.md

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+# CrowdSec Setup
+
+CrowdSec runs as a Docker (OCI) container on FredOS-Mediaserver. The firewall
+bouncer runs as a native NixOS service and talks to the containerised LAPI over
+localhost:8080.
+
+## Why Docker?
+
+The `crowdsec` package in nixpkgs unstable is incomplete — the NixOS module
+does not reliably set up the LAPI and hub collections. The official CrowdSec
+Docker image is well maintained and always up to date.
+
+## Architecture
+
+```
+[journald / log sources]
+        |
+   [CrowdSec LAPI]          ← Docker container (port 8080 on localhost)
+        |
+[firewall-bouncer]          ← Native NixOS service (nftables/iptables)
+```
+
+## Initial Setup (first deploy)
+
+After running `nixos-rebuild switch`, the CrowdSec container will be running
+but the firewall bouncer has no API key yet.
+
+**1. Generate a bouncer API key:**
+
+```bash
+docker exec crowdsec cscli bouncers add firewall-bouncer
+```
+
+Copy the key printed to stdout — it is only shown once.
+
+**2. Store the key on the machine:**
+
+```bash
+sudo mkdir -p /var/lib/secrets
+echo -n "PASTE_KEY_HERE" | sudo tee /var/lib/secrets/crowdsec-bouncer-key
+sudo chmod 600 /var/lib/secrets/crowdsec-bouncer-key
+sudo chown root:root /var/lib/secrets/crowdsec-bouncer-key
+```
+
+**3. Restart the bouncer:**
+
+```bash
+sudo systemctl restart crowdsec-firewall-bouncer
+sudo systemctl status crowdsec-firewall-bouncer
+```
+
+The key file at `/var/lib/secrets/crowdsec-bouncer-key` is not managed by Nix
+and must be created manually on each new machine. It should never be committed
+to git.
+
+## Re-registering the Bouncer
+
+If the bouncer loses its registration (e.g. after a container wipe):
+
+```bash
+# Remove the old registration
+docker exec crowdsec cscli bouncers delete firewall-bouncer
+
+# Re-add and capture the new key
+docker exec crowdsec cscli bouncers add firewall-bouncer
+
+# Update the key file and restart
+echo -n "NEW_KEY_HERE" | sudo tee /var/lib/secrets/crowdsec-bouncer-key
+sudo systemctl restart crowdsec-firewall-bouncer
+```
+
+## Useful Commands
+
+```bash
+# View active bouncers
+docker exec crowdsec cscli bouncers list
+
+# View active decisions (bans)
+docker exec crowdsec cscli decisions list
+
+# View alerts
+docker exec crowdsec cscli alerts list
+
+# Install/update a collection
+docker exec crowdsec cscli collections install crowdsecurity/sshd
+
+# View installed collections
+docker exec crowdsec cscli collections list
+```
+
+## Persistent Data
+
+The container mounts the following host paths:
+
+| Host path                        | Container path          | Purpose                  |
+|----------------------------------|-------------------------|--------------------------|
+| `/var/lib/crowdsec/data`         | `/var/lib/crowdsec/data`| GeoIP DB, decisions, etc |
+| `/var/lib/crowdsec/config`       | `/etc/crowdsec`         | Config, hub, bouncers    |
+| `/var/log/crowdsec`              | `/var/log/crowdsec`     | CrowdSec logs            |