Add demo scripts: egress IP check and bulk proxy creation

docs/demo/show-egress-ips.sh probes each healthy proxy from the
discovery API against an IP-echo site; create-kubernetes-proxies.sh and
create-gcp-proxies.sh bulk-create demo Proxies, the gcp one spreading
them across randomly picked EU zones.

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

docs/demo/create-kubernetes-proxies.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+# Demo: create N Managed proxies backed by the kubernetes-pod provider,
+# named proxy-kubernetes-demo-1 .. proxy-kubernetes-demo-N. Pods share the
+# cluster's egress IP — this exercises the full lifecycle, not distinct
+# egress paths (use create-gcp-proxies.sh for that).
+#
+# Usage:
+#   ./create-kubernetes-proxies.sh <count>
+#
+# Optional environment:
+#   NAMESPACE  namespace to create the proxies in (default: current context)
+set -euo pipefail
+
+if [ $# -ne 1 ] || ! [[ "$1" =~ ^[1-9][0-9]*$ ]]; then
+    echo "usage: $(basename "$0") <count>  (positive integer)" >&2
+    exit 1
+fi
+count="$1"
+
+if ! command -v kubectl &> /dev/null; then
+    echo "ERROR: kubectl is required but not installed" >&2
+    exit 1
+fi
+
+ns_args=()
+if [ -n "${NAMESPACE:-}" ]; then
+    ns_args=(-n "${NAMESPACE}")
+fi
+
+for i in $(seq 1 "${count}"); do
+    echo "Creating proxy-kubernetes-demo-${i} ..."
+    kubectl apply "${ns_args[@]}" -f - << EOF
+apiVersion: crawl.example.com/v1alpha1
+kind: Proxy
+metadata:
+  name: proxy-kubernetes-demo-${i}
+spec:
+  mode: Managed
+  provider: kubernetes
+  attributes:
+    geo: local
+    purpose: crawl
+EOF
+done
+
+echo ""
+echo "Created ${count} proxies. Watch them come up with:"
+echo "  kubectl get px ${ns_args[*]:-} -w"