fix(desktop): let status-stack titles use the full row before truncating

Todo, subagent, background, and preview titles in the composer status
stack were capped at an arbitrary max-w-[18rem], ellipsizing long items
way before the row ran out of space. The spans already live in the
shared StatusRow's min-w-0 flex-1 content slot, so plain truncate gives
correct overflow at the actual row edge — drop the cap.

apps/desktop/src/app/chat/composer/status-stack/preview-row.tsx

@@ -129,7 +129,7 @@ export const PreviewStatusRow = memo(function PreviewStatusRow({ item, onDismiss
           </span>
         }
       >
-        <span className="min-w-0 max-w-[18rem] truncate text-[0.73rem] leading-4 text-foreground/92">{item.label}</span>
+        <span className="min-w-0 truncate text-[0.73rem] leading-4 text-foreground/92">{item.label}</span>
       </Tip>
     </StatusRow>
   )

apps/desktop/src/app/chat/composer/status-stack/status-row.tsx

@@ -140,7 +140,7 @@ export const StatusItemRow = memo(function StatusItemRow({ item, onDismiss, onOp
       >
         <span
           className={cn(
-            'min-w-0 max-w-[18rem] truncate text-[0.73rem] leading-4',
+            'min-w-0 truncate text-[0.73rem] leading-4',
             failed
               ? 'text-destructive/90'
               : item.todoStatus && item.todoStatus !== 'in_progress'