backlog: Actually exit the for loop once we rendered the bottom paragraph

The first loop is more expensive due to computing the height before
rendering...

src/components/backlog.rs

@@ -85,6 +85,9 @@ impl Component for Backlog {
       text_area.height = text_area.height.saturating_sub(height);
 
       scroll = scroll.saturating_sub(expected_height);
+      if scroll == 0 {
+        break;
+      }
     }
     if text_area.height == 0 {
       // No more room to display other paragraphs, stop now