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/show-egress-ips.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+# Demo: list proxies from the discovery API and show the egress IP each
+# healthy one provides, by calling an IP-echo site through it.
+#
+# Usage:
+#   ./show-egress-ips.sh <BASE_URL>          e.g. ./show-egress-ips.sh localhost:8090
+#
+# Optional environment:
+#   TOKEN        bearer token for the discovery API (see docs/api.md)
+#   IP_ECHO_URL  site that returns the caller's IP as JSON
+#                (default: https://api.ipify.org?format=json)
+set -euo pipefail
+
+if [ $# -ne 1 ]; then
+    echo "usage: $(basename "$0") <BASE_URL>  (e.g. localhost:8090)" >&2
+    exit 1
+fi
+BASE_URL="$1"
+IP_ECHO_URL="${IP_ECHO_URL:-https://api.ipify.org?format=json}"
+
+for tool in curl jq; do
+    if ! command -v "${tool}" &> /dev/null; then
+        echo "ERROR: ${tool} is required but not installed" >&2
+        exit 1
+    fi
+done
+
+auth_args=()
+if [ -n "${TOKEN:-}" ]; then
+    auth_args=(-H "Authorization: Bearer ${TOKEN}")
+fi
+
+echo "Fetching proxies from ${BASE_URL}/v1/proxies ..."
+if ! proxies_json=$(curl -sS --fail "${auth_args[@]}" "${BASE_URL}/v1/proxies"); then
+    echo "ERROR: could not fetch proxy list from ${BASE_URL}" >&2
+    exit 1
+fi
+if ! echo "${proxies_json}" | jq -e . > /dev/null; then
+    echo "ERROR: response from ${BASE_URL}/v1/proxies is not valid JSON" >&2
+    exit 1
+fi
+
+total=$(echo "${proxies_json}" | jq -r '.count')
+echo "Found ${total} proxies"
+echo ""
+
+probed=0
+skipped=0
+failed=0
+while IFS= read -r proxy; do
+    id=$(echo "${proxy}" | jq -r '.id')
+    ip=$(echo "${proxy}" | jq -r '.ip')
+    port=$(echo "${proxy}" | jq -r '.port')
+    healthy=$(echo "${proxy}" | jq -r '.healthy')
+
+    if [ "${healthy}" != "true" ]; then
+        echo "--- skipping ${id} (unhealthy) ---"
+        echo ""
+        skipped=$((skipped + 1))
+        continue
+    fi
+
+    echo "=== via ${id} — http://${ip}:${port} ==="
+    if response=$(curl -sS --max-time 10 -x "http://${ip}:${port}" "${IP_ECHO_URL}"); then
+        echo "${response}" | jq . 2> /dev/null || echo "${response}"
+        probed=$((probed + 1))
+    else
+        echo "WARNING: request through ${id} failed" >&2
+        failed=$((failed + 1))
+    fi
+    echo ""
+done < <(echo "${proxies_json}" | jq -c '.proxies[]')
+
+echo "Done: ${total} proxies — ${probed} probed, ${skipped} skipped (unhealthy), ${failed} failed"