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/is-boolean-object/.editorconfig

@@ -0,0 +1,22 @@
+root = true
+
+[*]
+indent_style = tab
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+max_line_length = 150
+
+[CHANGELOG.md]
+indent_style = space
+indent_size = 2
+
+[.github/workflows/*.yml]
+indent_style = off
+indent_size = off
+max_line_length = off
+
+[{CHANGELOG.md,*.json}]
+max_line_length = off