fix: remove unused meta_name fields from meta plugin structs

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

src/meta_plugin/cwd.rs

@@ -3,7 +3,6 @@ use crate::meta_plugin::{MetaPlugin, MetaPluginType};
 
 #[derive(Debug, Clone, Default)]
 pub struct CwdMetaPlugin {
-    meta_name: String,
     is_finalized: bool,
     base: crate::meta_plugin::BaseMetaPlugin,
 }
@@ -34,7 +33,6 @@ impl CwdMetaPlugin {
         }
         
         CwdMetaPlugin {
-            meta_name: "cwd".to_string(),
             is_finalized: false,
             base,
         }