Standardize deployment env and deployer handling

scripts/deployment/deploy-sufficient-balance-chains.sh

@@ -27,21 +27,13 @@ elif [[ -n "${REPO_ROOT:-}" && -f "$REPO_ROOT/.env" ]]; then
   set +a
 fi
 
-# Load .env
-if [ -f .env ]; then
-  set -a
-  source .env
-  set +a
-fi
-
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
 RED='\033[0;31m'
 BLUE='\033[0;34m'
 NC='\033[0m'
 
-if [ -z "${PRIVATE_KEY:-}" ]; then
-  echo -e "${RED}ERROR: PRIVATE_KEY not set in .env${NC}"
+if ! require_private_key_env; then
   exit 1
 fi