Implement DATEV export functionality in DataViewer and enhance TransactionsTable with selection features and improved row styling. Update environment variables and add devServer configuration in webpack for better development experience.

client/src/components/cellRenderers/RecipientRenderer.js

@@ -1,9 +1,39 @@
 import React from 'react';
 
 const RecipientRenderer = (params) => {
+  const isIbanColumn = params.colDef.field === 'Kontonummer/IBAN';
+  const value = params.value;
+
+  const handleClick = (event) => {
+    if (isIbanColumn && value && params.api) {
+      // Stop event propagation to prevent row selection
+      event.stopPropagation();
+      
+      // Apply filter to IBAN column using the custom IbanSelectionFilter format
+      const currentFilterModel = params.api.getFilterModel();
+      params.api.setFilterModel({
+        ...currentFilterModel,
+        'Kontonummer/IBAN': {
+          filterType: 'iban-selection',
+          values: [value]
+        }
+      });
+    }
+  };
+
   return (
-    <span style={{ fontSize: '0.7rem', lineHeight: '1.2' }}>
-      {params.value}
+    <span 
+      style={{ 
+        fontSize: '0.7rem', 
+        lineHeight: '1.2',
+        cursor: isIbanColumn && value ? 'pointer' : 'default',
+        color: isIbanColumn && value ? '#1976d2' : 'inherit',
+        textDecoration: isIbanColumn && value ? 'underline' : 'none'
+      }}
+      onClick={isIbanColumn && value ? handleClick : undefined}
+      title={isIbanColumn && value ? `Nach IBAN "${value}" filtern` : undefined}
+    >
+      {value}
     </span>
   );
 };