Website restoration: Node.js backend, restored design, GitHub sync disabled

- Replaced broken .NET backend with Node.js/Express
- Restored original website design with purple gradient hero
- Updated homepage and shop pages with Bootstrap 5 responsive design
- Disabled GitHub remote sync - all code now stored locally only
- Created backup scripts and documentation
- All changes saved on Ubuntu server at /var/www/SkyArtShop

backend/node_modules/validator/lib/isLuhnNumber.js

@@ -0,0 +1,34 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = isLuhnNumber;
+var _assertString = _interopRequireDefault(require("./util/assertString"));
+function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
+function isLuhnNumber(str) {
+  (0, _assertString.default)(str);
+  var sanitized = str.replace(/[- ]+/g, '');
+  var sum = 0;
+  var digit;
+  var tmpNum;
+  var shouldDouble;
+  for (var i = sanitized.length - 1; i >= 0; i--) {
+    digit = sanitized.substring(i, i + 1);
+    tmpNum = parseInt(digit, 10);
+    if (shouldDouble) {
+      tmpNum *= 2;
+      if (tmpNum >= 10) {
+        sum += tmpNum % 10 + 1;
+      } else {
+        sum += tmpNum;
+      }
+    } else {
+      sum += tmpNum;
+    }
+    shouldDouble = !shouldDouble;
+  }
+  return !!(sum % 10 === 0 ? sanitized : false);
+}
+module.exports = exports.default;
+module.exports.default = exports.default;