Fix fail2ban crash: disable default sshd jail, make non-fatal

Alpine's fail2ban ships with sshd jail enabled by default. Since there's
no SSH server in the Fly.io container, fail2ban exits with an error
looking for sshd logs — crashing the container via set -e.

Disable the sshd jail explicitly and make fail2ban startup non-fatal
since nginx rate limiting is the primary defense.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

fly/fail2ban/jail.d/forge.conf

@@ -1,3 +1,7 @@
+# Disable the default sshd jail — no SSH server in this container
+[sshd]
+enabled = false
+
 [forge-login]
 enabled  = true
 filter   = forge-login

fly/start.sh

@@ -20,9 +20,13 @@ nginx -g "daemon off;" &
 NGINX_PID=$!
 echo "Nginx started"
 
-# Start fail2ban for login brute-force protection
-fail2ban-server -b
-echo "fail2ban started"
+# Start fail2ban for login brute-force protection.
+# Non-fatal — nginx rate limiting is the primary defense; fail2ban is additive.
+if fail2ban-server -b; then
+    echo "fail2ban started"
+else
+    echo "WARNING: fail2ban failed to start (nginx rate limiting still active)"
+fi
 
 # Start Alloy for observability (logs → Loki, metrics → Prometheus)
 alloy run /etc/alloy/config.alloy \