refactor: Simplify filter plugin return values and apply io::copy directly

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

src/filter_plugin/skip.rs

@@ -30,8 +30,7 @@ impl FilterPlugin for SkipBytesFilter {
         }
         
         // Copy the remaining data using io::copy for efficiency
-        std::io::copy(reader, writer)?;
-        Ok(())
+        std::io::copy(reader, writer)
     }
 }
 

src/filter_plugin/strip_ansi.rs

@@ -14,7 +14,6 @@ impl FilterPlugin for StripAnsiFilter {
     fn filter<R: Read, W: Write>(&mut self, reader: &mut R, writer: &mut W) -> Result<()> {
         let mut ansi_writer = Writer::new(writer);
         std::io::copy(reader, &mut ansi_writer)?;
-        ansi_writer.flush()?;
-        Ok(())
+        ansi_writer.flush()
     }
 }