feat(gtm): Implement Rich Session Browser UI

- Replaced the basic session list with a dedicated, card-based Session Browser page.
- Each session card now displays product name, category, description, and a thumbnail placeholder for better usability.
- Updated the backend DB manager to extract this rich information from the existing JSON data store.
- Refactored the frontend (App.tsx, types.ts) to support the new UI and data structure.
- Added new component SessionBrowser.tsx and its corresponding CSS.
- Updated documentation to reflect the v2.6 changes.

gtm-architect/components/SessionBrowser.tsx

@@ -0,0 +1,58 @@
+import React from 'react';
+import { ProjectHistoryItem } from './types';
+import './SessionBrowser.css';
+
+interface SessionBrowserProps {
+  sessions: ProjectHistoryItem[];
+  onLoadSession: (projectId: string) => void;
+  onDeleteSession: (projectId: string) => void;
+}
+
+const SessionBrowser: React.FC<SessionBrowserProps> = ({ sessions, onLoadSession, onDeleteSession }) => {
+  
+  const getCategoryIcon = (category: string) => {
+    switch (category.toLowerCase()) {
+      case 'reinigungsroboter':
+        return '🧹'; // Sweeping broom emoji
+      case 'serviceroboter':
+        return '🛎️'; // Bellhop bell emoji
+      case 'transportroboter':
+        return '📦'; // Package emoji
+      case 'security roboter':
+        return '🛡️'; // Shield emoji
+      default:
+        return '🤖'; // Default robot emoji
+    }
+  };
+
+  return (
+    <div className="session-browser">
+      <h2>Gespeicherte Sitzungen</h2>
+      <div className="session-grid">
+        {sessions.map((session) => (
+          <div key={session.id} className="session-card">
+            <div className="card-header">
+                <span className="category-icon">{getCategoryIcon(session.productCategory)}</span>
+                <h3 title={session.productName}>{session.productName}</h3>
+            </div>
+            {/* Thumbnail placeholder */}
+            <div className="thumbnail-placeholder">
+              <span>🖼️</span>
+              <p>Thumbnail</p>
+            </div>
+            <div className="card-content">
+              <p className="product-description">{session.productDescription}</p>
+              <p className="last-updated">Zuletzt bearbeitet: {new Date(session.updated_at).toLocaleString()}</p>
+            </div>
+            <div className="card-actions">
+              <button onClick={() => onLoadSession(session.id)} className="load-btn">Laden</button>
+              <button onClick={() => onDeleteSession(session.id)} className="delete-btn">Löschen</button>
+            </div>
+          </div>
+        ))}
+      </div>
+    </div>
+  );
+};
+
+export default SessionBrowser;