[KM-497] [DED][FE] Fix chat response formatting and document hover tooltip

- Re-fetch room messages from API after stream completes to ensure
rendered content matches stored content (fixes formatting not matching
page-refresh behavior)
- Skip preprocessMarkdown during active streaming to prevent regex
processing incomplete markdown chunks
- Add title attribute to document filename for full name on hover

src/app/components/KnowledgeManagement.tsx

@@ -521,7 +521,7 @@ export default function KnowledgeManagement({
                           <FileText className="w-4 h-4 text-red-400" />
                         </div>
                         <div className="flex-1 min-w-0">
-                          <p className="text-sm font-medium text-slate-800 truncate">
+                          <p className="text-sm font-medium text-slate-800 truncate" title={doc.filename}>
                             {doc.filename}
                           </p>
                           <p className="text-xs text-slate-400">

src/app/components/Main.tsx

@@ -478,6 +478,9 @@ export default function Main() {
           }
         }
       }
+      // Re-fetch from API after stream ends to get the authoritative
+      // stored content — guarantees formatting matches page-refresh behavior
+      await loadRoomMessages(roomId);
     } catch (err: unknown) {
       if ((err as Error).name !== "AbortError") {
         setChats((prev) =>
@@ -751,7 +754,9 @@ export default function Main() {
                       rehypePlugins={[rehypeKatex]}
                       components={markdownComponents}
                     >
-                      {preprocessMarkdown(message.content)}
+                      {streamingMsgId === message.id
+                        ? message.content
+                        : preprocessMarkdown(message.content)}
                     </ReactMarkdown>
                   </div>
                 )}