Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/tough-cookie/lib/utilHelper.js

@@ -0,0 +1,39 @@
+function requireUtil() {
+  try {
+    // eslint-disable-next-line no-restricted-modules
+    return require("util");
+  } catch (e) {
+    return null;
+  }
+}
+
+// for v10.12.0+
+function lookupCustomInspectSymbol() {
+  return Symbol.for("nodejs.util.inspect.custom");
+}
+
+// for older node environments
+function tryReadingCustomSymbolFromUtilInspect(options) {
+  const _requireUtil = options.requireUtil || requireUtil;
+  const util = _requireUtil();
+  return util ? util.inspect.custom : null;
+}
+
+exports.getUtilInspect = function getUtilInspect(fallback, options = {}) {
+  const _requireUtil = options.requireUtil || requireUtil;
+  const util = _requireUtil();
+  return function inspect(value, showHidden, depth) {
+    return util ? util.inspect(value, showHidden, depth) : fallback(value);
+  };
+};
+
+exports.getCustomInspectSymbol = function getCustomInspectSymbol(options = {}) {
+  const _lookupCustomInspectSymbol =
+    options.lookupCustomInspectSymbol || lookupCustomInspectSymbol;
+
+  // get custom inspect symbol for node environments
+  return (
+    _lookupCustomInspectSymbol() ||
+    tryReadingCustomSymbolFromUtilInspect(options)
+  );
+};