refactor: Improve error handling and borrowing in item services

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/services/item_service.rs

@@ -59,7 +59,7 @@ impl<R: Read> Read for FilteringReader<R> {
         }
 
         // Process through the filter chain if it exists
-        if let Some(chain) = &mut self.filter_chain {
+        if let Some(ref mut chain) = self.filter_chain {
             // Use a cursor to read the input data
             let mut input_cursor = std::io::Cursor::new(&temp_buf[..bytes_read]);
             // Write filtered output to our buffer