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/isBtcAddress.js

@@ -0,0 +1,16 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = isBtcAddress;
+var _assertString = _interopRequireDefault(require("./util/assertString"));
+function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
+var bech32 = /^(bc1|tb1|bc1p|tb1p)[ac-hj-np-z02-9]{39,58}$/;
+var base58 = /^(1|2|3|m)[A-HJ-NP-Za-km-z1-9]{25,39}$/;
+function isBtcAddress(str) {
+  (0, _assertString.default)(str);
+  return bech32.test(str) || base58.test(str);
+}
+module.exports = exports.default;
+module.exports.default = exports.default;