fix(deploy): add warning messages for missing Docker secrets

docker-compose.staging.yml

@@ -98,6 +98,8 @@ services:
           chown www-data:www-data "$$SECRETS_DIR/db_user_password"
           export DB_PASSWORD_FILE="$$SECRETS_DIR/db_user_password"
           echo "✅ Copied db_user_password to $$SECRETS_DIR/db_user_password"
+        else
+          echo "⚠️  Warning: /run/secrets/db_user_password not found"
         fi
 
         if [ -f /run/secrets/app_key ]; then
@@ -106,6 +108,8 @@ services:
           chown www-data:www-data "$$SECRETS_DIR/app_key"
           export APP_KEY_FILE="$$SECRETS_DIR/app_key"
           echo "✅ Copied app_key to $$SECRETS_DIR/app_key"
+        else
+          echo "⚠️  Warning: /run/secrets/app_key not found"
         fi