Fix cargo fmt formatting and diarize threading test mock

src-tauri/src/commands/ai.rs

@@ -39,7 +39,11 @@ pub fn ai_chat(
     if response.msg_type == "error" {
         return Err(format!(
             "AI error: {}",
-            response.payload.get("message").and_then(|v| v.as_str()).unwrap_or("unknown")
+            response
+                .payload
+                .get("message")
+                .and_then(|v| v.as_str())
+                .unwrap_or("unknown")
         ));
     }