fix: resolve mutable borrow error in text plugin

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

src/meta_plugin/text.rs

@@ -216,7 +216,8 @@ impl MetaPlugin for TextMetaPlugin {
         if self.is_binary_content == Some(false) && !self.buffer.is_empty() {
             // Count any remaining words/lines in the buffer if we haven't already
             if self.word_count == 0 && self.line_count == 0 {
-                self.count_text_stats(&self.buffer);
+                let buffer_copy = self.buffer.clone();
+                self.count_text_stats(&buffer_copy);
             }
             
             if let Some(meta_data) = crate::meta_plugin::process_metadata_outputs(