fix: Build-Fehler — topic.keywords → topic.keyword_freq [appimage]

Übersehene Referenz in get_kb_session_status() nach Rename.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/knowledge.rs

@@ -1287,7 +1287,7 @@ pub async fn get_kb_session_status() -> Result<String, String> {
     let topic = SESSION_TOPIC.lock().unwrap();
     Ok(format!(
         "Keywords: {} | Shown: {} | Messages: {} | Project: {}",
-        topic.keywords.len(),
+        topic.keyword_freq.len(),
         topic.shown_ids.len(),
         topic.message_count,
         topic.last_project.as_deref().unwrap_or("none")