refactor: update meta plugins to use new trait interface

Co-authored-by: aider (openai/andrew/openrouter/mistralai/mistral-medium-3.1) <aider@aider.chat>

src/meta_plugin/digest.rs

@@ -160,11 +160,11 @@ impl MetaPlugin for ReadTimeMetaPlugin {
         true
     }
     
-    fn finalize(&mut self, _conn: &Connection) -> Result<()> {
-        Ok(())
+    fn finalize(&mut self) -> Result<PluginResponse> {
+        Ok(PluginResponse::default())
     }
 
-    fn update(&mut self, _data: &[u8], _conn: &Connection) {
+    fn update(&mut self, _data: &[u8]) -> Result<PluginResponse> {
         if self.start_time.is_none() {
             self.start_time = Some(Instant::now());
         }
@@ -251,16 +251,37 @@ impl MetaPlugin for ReadRateMetaPlugin {
     fn is_internal(&self) -> bool {
         true
     }
-    
-    fn finalize(&mut self, _conn: &Connection) -> Result<()> {
-        Ok(())
+
+    fn finalize(&mut self) -> Result<PluginResponse> {
+        let mut metadata = Vec::new();
+
+        if let Some(start_time) = self.start_time {
+            if let Some(item_id) = self.item_id {
+                let duration = start_time.elapsed();
+                let rate = if duration.as_secs_f64() > 0.0 {
+                    format!("{:.2} KB/s", (self.bytes_read as f64 / 1024.0) / duration.as_secs_f64())
+                } else {
+                    "N/A".to_string()
+                };
+
+                if let Some(meta) = self.create_meta(item_id, "read_rate", rate) {
+                    metadata.push(meta);
+                }
+            }
+        }
+
+        Ok(PluginResponse {
+            metadata: Some(metadata),
+            is_finalized: true,
+        })
     }
 
-    fn update(&mut self, data: &[u8], _conn: &Connection) {
+    fn update(&mut self, data: &[u8]) -> Result<PluginResponse> {
         if self.start_time.is_none() {
             self.start_time = Some(Instant::now());
         }
         self.bytes_read += data.len() as u64;
+        Ok(PluginResponse::default())
     }
 
     fn meta_name(&self) -> String {