feat: add geth network info helper

Added the geth-net-info.sh script, which displays the chainId and last block number for a running geth via RPC.

scripts/geth-net-info.sh

@@ -0,0 +1,31 @@
+```bash
+#!/usr/bin/env bash
+set -euo pipefail
+```
+
+# Prints basic network information by attaching to a running geth instance.
+#
+# Usage:
+#   ./scripts/geth-net-info.sh
+#
+# By default it attaches to http://127.0.0.1:8545. Override via:
+#   RPC_URL=http://host:port ./scripts/geth-net-info.sh
+
+RPC_URL="${RPC_URL:-http://127.0.0.1:8545}"
+
+echo "Using RPC URL: ${RPC_URL}"
+echo
+
+payload='{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}'
+chain_id=$(curl -s -X POST "${RPC_URL}" -H "Content-Type: application/json" -d "${payload}" | jq -r '.result // empty')
+
+if [ -z "${chain_id}" ]; then
+  echo "Failed to fetch chainId. Is geth running and RPC enabled?"
+  exit 1
+fi
+
+payload_block='{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
+block_number=$(curl -s -X POST "${RPC_URL}" -H "Content-Type: application/json" -d "${payload_block}" | jq -r '.result // empty')
+
+echo "chainId: ${chain_id}"
+echo "latest block: ${block_number}"