refactor: migrate from ingress-nginx to Traefik v3 (#254)

## Summary

- Replace ingress-nginx 4.15.1 with Traefik v3 (Helm chart 39.0.7) as ingress controller
- Convert nginx-specific annotations to Traefik Middleware CRDs
- Update setup script selectors, namespaces, and readiness checks
- Add `.claude/settings.local.json` to `.gitignore`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #254

setup

@@ -12,20 +12,20 @@ kubectl create secret docker-registry gitlab \
 
 kubectl patch serviceaccount default -p '{"imagePullSecrets": [{"name": "gitlab"}]}'
 
-kustomized="$(mktemp -t unboundnginx.yaml.XXXXXX)"
+kustomized="$(mktemp -t unboundtraefik.yaml.XXXXXX)"
 
-kubectl kustomize --enable-helm "k8s/nginx" >> "${kustomized}"
+kubectl kustomize --enable-helm "k8s/traefik" >> "${kustomized}"
 kubectl apply -f "${kustomized}" --server-side || true
 
-printf "\nWait for pod app.kubernetes.io/component=controller to be created."
+printf "\nWait for pod app.kubernetes.io/name=traefik to be created."
 while :; do
   sleep 2
-  [ -n "$(kubectl -n ingress-nginx get pod --selector=app.kubernetes.io/component=controller 2>/dev/null)" ] && printf "\n\n" && break
+  [ -n "$(kubectl -n traefik get pod --selector=app.kubernetes.io/name=traefik 2>/dev/null)" ] && printf "\n\n" && break
   printf "."
 done
 
-echo "Wait for nginx to be available."
-until [[ $(kubectl -n ingress-nginx get endpointslices -l 'kubernetes.io/service-name=ingress-nginx-controller' -o=jsonpath='{.items[*].endpoints[*].addresses[*]}') ]]; do sleep 5; done
+echo "Wait for traefik to be available."
+until [[ $(kubectl -n traefik get endpointslices -l 'kubernetes.io/service-name=traefik' -o=jsonpath='{.items[*].endpoints[*].addresses[*]}') ]]; do sleep 5; done
 
 kustomized="$(mktemp -t unboundinfra.yaml.XXXXXX)"