fix: implement proper finalize method to capture command output

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

src/meta_plugin/program.rs

@@ -64,7 +64,28 @@ impl MetaPlugin for MetaPluginProgram {
     }
 
     fn finalize(&mut self) -> io::Result<String> {
-        Ok("program".to_string())
+        let program = self.program.clone();
+        let args = self.args.clone();
+
+        debug!("META: Executing command for finalize: {:?} {:?}", program, args);
+
+        let output = Command::new(program)
+            .args(args)
+            .stdin(Stdio::null())
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped())
+            .output()?;
+
+        if output.status.success() {
+            let stdout = String::from_utf8_lossy(&output.stdout);
+            Ok(stdout.trim().to_string())
+        } else {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            Err(io::Error::new(
+                io::ErrorKind::Other,
+                format!("Command failed: {}", stderr.trim()),
+            ))
+        }
     }
 
     fn update(&mut self, _data: &[u8]) {