Add PDF inline preview support to knowledge base viewer

frontend/src/components/KnowledgeBaseViewer.js

@@ -191,15 +191,27 @@ export default function KnowledgeBaseViewer({ article, onClose }) {
 
             {/* PDF */}
             {isPDF && (
-              <div className="text-center py-12">
+              <div className="w-full" style={{ height: '700px' }}>
-                <File className="w-16 h-16 mx-auto mb-4" style={{ color: '#EF4444' }} />
+                <iframe
-                <p className="mb-4" style={{ color: '#94A3B8' }}>
+                  src={`${API_BASE}/knowledge-base/${article.id}/content`}
-                  PDF Preview not available. Click the download button to view this file.
+                  title={article.title}
-                </p>
+                  className="w-full h-full rounded"
-                <button onClick={handleDownload} className="intel-button intel-button-success">
+                  style={{
-                  <Download className="w-4 h-4 mr-2" />
+                    border: '1px solid rgba(14, 165, 233, 0.3)',
-                  Download PDF
+                    background: 'rgba(15, 23, 42, 0.8)'
-                </button>
+                  }}
+                >
+                  <div className="text-center py-12">
+                    <File className="w-16 h-16 mx-auto mb-4" style={{ color: '#EF4444' }} />
+                    <p className="mb-4" style={{ color: '#94A3B8' }}>
+                      Your browser doesn't support PDF preview. Click the download button to view this file.
+                    </p>
+                    <button onClick={handleDownload} className="intel-button intel-button-success">
+                      <Download className="w-4 h-4 mr-2" />
+                      Download PDF
+                    </button>
+                  </div>
+                </iframe>
               </div>
             )}