Episode 12/13: CrowdSec next to fail2ban, and an AppSec WAF in Caddy

Measured on the demo box against the same 24h of real traffic.

Episode 12 (detection, blocklist, firewall):
- crowdsec/ with install notes and the traps: port 8080 clash, empty first
  blocklist pull, replay forensic-mode dropping events (FIFO workaround),
  ssh-time-based-bf shipping remediation:false, the AppSec collections that
  refuse to start without extra rules.
- firewall bouncer in nftables mode (input + forward), which blocks
  Docker-published ports and survives ufw reload; iptables/DOCKER-USER does not.
- HARDENING.md episode 12 section with the numbers: fail2ban 4 banned IPs vs
  CrowdSec 23 detected / 1 blocked, blocklist overlap 50% of IPs but 19% of
  attempts, and the mode=normal blind spot for key-only root attempts.

Episode 13 (AppSec WAF):
- caddy/Dockerfile now builds the CrowdSec bouncer and AppSec handler alongside
  rate-limit, pinned to v0.14.1.
- Caddyfile imports a crowdsec snippet (bouncer + appsec) on every site except
  vpn; compose passes CROWDSEC_BOUNCER_KEY and host.docker.internal.
- Measured: virtual patching blocks known CVEs only (7 of 41 probes, near-zero
  false positives); OWASP CRS raises that to 27 of 41 but breaks git push and
  wiki editing at default paranoia. Default stays vpatch+generic.

fail2ban config unchanged. No secrets or real domains/IPs in tracked files.

README.md

@@ -247,6 +247,12 @@ security updates, pinned image tags, offsite backups. The ready-to-paste configs
 from episode 10 (ufw `after.rules`, fail2ban jails and filter, sshd drop-in) live
 in **[hardening/](hardening/)**.
 
+Episode 12 adds CrowdSec next to fail2ban (not instead of it): community
+blocklist, a firewall bouncer in nftables mode that Docker cannot bypass, and an
+AppSec WAF inside Caddy. Install notes and the traps we measured are in
+**[crowdsec/](crowdsec/)**. Note the Caddy image now needs the key
+`CROWDSEC_BOUNCER_KEY` in `.env`.
+
 ---
 
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