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/lib/rules/no-octal.js

@@ -0,0 +1,45 @@
+/**
+ * @fileoverview Rule to flag when initializing octal literal
+ * @author Ilya Volodin
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Disallow octal literals",
+            recommended: true,
+            url: "https://eslint.org/docs/latest/rules/no-octal"
+        },
+
+        schema: [],
+
+        messages: {
+            noOctal: "Octal literals should not be used."
+        }
+    },
+
+    create(context) {
+
+        return {
+
+            Literal(node) {
+                if (typeof node.value === "number" && /^0[0-9]/u.test(node.raw)) {
+                    context.report({
+                        node,
+                        messageId: "noOctal"
+                    });
+                }
+            }
+        };
+
+    }
+};