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/eslint-plugin-react/lib/util/eslint.js

@@ -0,0 +1,46 @@
+'use strict';
+
+function getSourceCode(context) {
+  return context.getSourceCode ? context.getSourceCode() : context.sourceCode;
+}
+
+function getAncestors(context, node) {
+  const sourceCode = getSourceCode(context);
+  return sourceCode.getAncestors ? sourceCode.getAncestors(node) : context.getAncestors();
+}
+
+function getScope(context, node) {
+  const sourceCode = getSourceCode(context);
+  if (sourceCode.getScope) {
+    return sourceCode.getScope(node);
+  }
+
+  return context.getScope();
+}
+
+function markVariableAsUsed(name, node, context) {
+  const sourceCode = getSourceCode(context);
+  return sourceCode.markVariableAsUsed
+    ? sourceCode.markVariableAsUsed(name, node)
+    : context.markVariableAsUsed(name);
+}
+
+function getFirstTokens(context, node, count) {
+  const sourceCode = getSourceCode(context);
+  return sourceCode.getFirstTokens ? sourceCode.getFirstTokens(node, count) : context.getFirstTokens(node, count);
+}
+
+function getText(context) {
+  const sourceCode = getSourceCode(context);
+  const args = Array.prototype.slice.call(arguments, 1);
+  return sourceCode.getText ? sourceCode.getText.apply(sourceCode, args) : context.getSource.apply(context, args);
+}
+
+module.exports = {
+  getAncestors,
+  getFirstTokens,
+  getScope,
+  getSourceCode,
+  getText,
+  markVariableAsUsed,
+};