feat: add world map functionality and admin map management

- Added world map page with interactive marker display
- Implemented admin map management for marker CRUD operations
- Added map layers and markers seed data to database
- Integrated new routes for map functionality
- Updated database configuration for production environment
- Added documentation page route
- Enhanced package.json with required dependencies for map features

components/MarkdownEditor.tsx

@@ -1,4 +1,6 @@
 import React, { useState, useRef } from 'react';
+import ReactMarkdown from 'react-markdown';
+import remarkGfm from 'remark-gfm';
 import { Icons } from './IconSet';
 
 interface MarkdownEditorProps {
@@ -95,15 +97,24 @@ const MarkdownEditor: React.FC<MarkdownEditorProps> = ({ value, onChange, classN
         ))}
       </div>
 
-      {/* Textarea */}
-      <textarea
-        ref={textareaRef}
-        value={value}
-        onChange={(e) => onChange(e.target.value)}
-        className="w-full h-64 md:h-96 bg-[#0b0b0d] border-0 p-4 text-sm font-mono text-gray-300 focus:outline-none resize-none"
-        placeholder="Schreibe dein Journal hier... Verwende die Toolbar für Formatierung."
-        spellCheck={false}
-      />
+      {/* Editor and Preview */}
+      <div className="flex h-64 md:h-96">
+        {/* Textarea */}
+        <textarea
+          ref={textareaRef}
+          value={value}
+          onChange={(e) => onChange(e.target.value)}
+          className="w-1/2 h-full bg-[#0b0b0d] border-0 border-r border-border p-4 text-sm font-mono text-gray-300 focus:outline-none resize-none"
+          placeholder="Schreibe dein Journal hier... Verwende die Toolbar für Formatierung."
+          spellCheck={false}
+        />
+        {/* Preview */}
+        <div className="w-1/2 h-full bg-[#0b0b0d] p-4 text-sm text-gray-300 overflow-auto">
+          <ReactMarkdown remarkPlugins={[remarkGfm]}>
+            {value || 'Hier erscheint die Vorschau deiner Markdown-Formatierung.'}
+          </ReactMarkdown>
+        </div>
+      </div>
 
       {/* Footer */}
       <div className="bg-surfaceHighlight border-t border-border px-4 py-2 text-xs text-textMuted">