fix: add JWT secret validation to geth-entrypoint

geth/geth-entrypoint was missing the same BASE_NODE_L2_ENGINE_AUTH_RAW
validation added to reth-entrypoint, base-consensus-entrypoint, and
op-node-entrypoint. Without this check, geth nodes using the default
or placeholder secret would silently start with a public JWT.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: erhnysr

geth/geth-entrypoint

@@ -28,6 +28,12 @@ fi
 
 mkdir -p $GETH_DATA_DIR
 
+if [[ -z "${BASE_NODE_L2_ENGINE_AUTH_RAW:-}" || "${BASE_NODE_L2_ENGINE_AUTH_RAW}" == "<your-secret-jwt>" ]]; then
+    echo "ERROR: BASE_NODE_L2_ENGINE_AUTH_RAW is not set." >&2
+    echo "Generate a secret and set it in your .env file:" >&2
+    echo "  BASE_NODE_L2_ENGINE_AUTH_RAW=\$(openssl rand -hex 32)" >&2
+    exit 1
+fi
 echo "$BASE_NODE_L2_ENGINE_AUTH_RAW" > "$BASE_NODE_L2_ENGINE_AUTH"
 
 if [ "${OP_GETH_ETH_STATS+x}" = x ]; then