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/ajv-keywords/keywords/dot/patternRequired.jst

@@ -0,0 +1,33 @@
+{{# def.definitions }}
+{{# def.errors }}
+{{# def.setupKeyword }}
+
+{{
+  var $key = 'key' + $lvl
+    , $idx = 'idx' + $lvl
+    , $matched = 'patternMatched' + $lvl
+    , $dataProperties = 'dataProperties' + $lvl
+    , $closingBraces = ''
+    , $ownProperties = it.opts.ownProperties;
+}}
+
+var {{=$valid}} = true;
+{{? $ownProperties }}
+  var {{=$dataProperties}} = undefined;
+{{?}}
+
+{{~ $schema:$pProperty }}
+  var {{=$matched}} = false;
+  {{# def.iterateProperties }}
+    {{=$matched}} = {{= it.usePattern($pProperty) }}.test({{=$key}});
+    if ({{=$matched}}) break;
+  }
+
+  {{ var $missingPattern = it.util.escapeQuotes($pProperty); }}
+  if (!{{=$matched}}) {
+    {{=$valid}} = false;
+    {{# def.addError:'patternRequired' }}
+  } {{# def.elseIfValid }}
+{{~}}
+
+{{= $closingBraces }}