fix(traefik): stop fail2ban banning legit traffic on stray 4xx

statuscode "400,401,403-499" counted almost every client error as a
brute-force strike, so normal 404s/400s from routine app behavior could
rack up 5 hits in 10 minutes and trip a 3h ban (returned as 429) for real
users. Narrow to 401/403 (actual auth failures) and raise maxretry to 15
so it still catches real brute-forcing without false-positiving on noise.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

traefik/dynamic/fail2ban.yaml

@@ -10,6 +10,6 @@ http:
           rules:
             bantime: "3h"
             findtime: "10m"
-            maxretry: 5
+            maxretry: 15
             enabled: true
-            statuscode: "400,401,403-499"
+            statuscode: "401,403"