Standardize deployment env and deployer handling

scripts/deployment/deploy-all-ready-chains.sh

@@ -25,11 +25,6 @@ elif [[ -n "${REPO_ROOT:-}" && -f "$REPO_ROOT/.env" ]]; then
   set +a
 fi
 
-# Source environment
-if [ -f .env ]; then
-    source .env
-fi
-
 # Colors
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
@@ -43,8 +38,7 @@ echo -e "${BLUE}========================================${NC}"
 echo ""
 
 # Check prerequisites
-if [ -z "${PRIVATE_KEY:-}" ]; then
-    echo -e "${RED}✗ PRIVATE_KEY not set in .env${NC}"
+if ! require_private_key_env; then
     exit 1
 fi