feat: Add units to read_rate and read_time meta plugins

Co-authored-by: aider (openai/andrew.openrouter.qwen.qwen3-coder) <aider@aider.chat>

src/meta_plugin/digest.rs

@@ -80,9 +80,9 @@ impl MetaPlugin for ReadTimeMetaPlugin {
     fn finalize(&mut self) -> io::Result<String> {
         if let Some(start_time) = self.start_time {
             let duration = start_time.elapsed();
-            Ok(format!("{:.6}", duration.as_secs_f64()))
+            Ok(format!("{:.6}s", duration.as_secs_f64()))
         } else {
-            Ok("0.000000".to_string())
+            Ok("0.000000s".to_string())
         }
     }
 
@@ -125,12 +125,12 @@ impl MetaPlugin for ReadRateMetaPlugin {
             let duration = start_time.elapsed();
             if duration.as_secs_f64() > 0.0 {
                 let rate = self.bytes_read as f64 / duration.as_secs_f64();
-                Ok(format!("{:.0}", rate))
+                Ok(format!("{:.0} B/s", rate))
             } else {
-                Ok("0".to_string())
+                Ok("0 B/s".to_string())
             }
         } else {
-            Ok("0".to_string())
+            Ok("0 B/s".to_string())
         }
     }