refactor(enhance): fold lowercase helpers into single owned function

use_lowercase_owned disappears; the surviving use_lowercase takes the
owned Mapping and borrowed callers clone at the call site.

src-tauri/src/enhance/field.rs

@@ -24,11 +24,7 @@ fn lowercase_key(key: &str) -> Value {
     Value::from(key.as_str())
 }
 
-pub fn use_lowercase(config: &Mapping) -> Mapping {
-    use_lowercase_owned(config.clone())
-}
-
-pub fn use_lowercase_owned(config: Mapping) -> Mapping {
+pub fn use_lowercase(config: Mapping) -> Mapping {
     let mut lowercased = Mapping::new();
 
     for (key, value) in config {

src-tauri/src/enhance/merge.rs

@@ -17,7 +17,7 @@ fn deep_merge(a: &mut Value, b: Value) {
 }
 
 pub fn use_merge(merge: &Mapping, mut config: Mapping) -> Mapping {
-    for (key, value) in use_lowercase(merge) {
+    for (key, value) in use_lowercase(merge.clone()) {
         match (config.get_mut(&key), value) {
             (Some(Value::Mapping(existing)), Value::Mapping(overlay)) if key.as_str() == Some("dns") => {
                 existing.extend(overlay);

src-tauri/src/enhance/mod.rs

@@ -8,7 +8,7 @@ mod tun;
 
 use self::{
     chain::{AsyncChainItemFrom as _, ChainItem, ChainType},
-    field::{use_keys, use_lowercase_owned, use_sort},
+    field::{use_keys, use_lowercase, use_sort},
     merge::use_merge,
     script::use_script,
     seq::{SeqMap, use_seq},
@@ -614,7 +614,7 @@ fn apply_builtin_scripts(mut config: Mapping, clash_core: Option<String>, enable
             .collect();
         if !items.is_empty() {
             // The JS path saw a lowercased view; lowercase once, only when a builtin runs.
-            config = use_lowercase_owned(config);
+            config = use_lowercase(config);
             for item in items {
                 logging!(debug, Type::Core, "run builtin script {}", item.uid);
                 config = match item.uid.as_str() {

src-tauri/src/enhance/script.rs

@@ -1,6 +1,6 @@
 use crate::{process::AsyncHandler, utils::tmpl};
 
-use super::field::{use_lowercase, use_lowercase_owned};
+use super::field::use_lowercase;
 use anyhow::{Error, Result};
 use boa_engine::{Context, JsString, JsValue, Source, js_string, native_function::NativeFunction, property::Attribute};
 use clash_verge_logging::{Type, logging};
@@ -22,10 +22,10 @@ type EvalOutcome = (Result<Mapping, std::string::String>, Vec<(String, String)>)
 pub(super) async fn use_script(script: String, config: Mapping, name: String) -> ScriptResult {
     // The template is identity-plus-lowercasing; skip the Boa round-trip.
     if script == tmpl::ITEM_SCRIPT {
-        return (use_lowercase_owned(config), vec![], vec![]);
+        return (use_lowercase(config), vec![], vec![]);
     }
 
-    let json = match serde_json::to_string(&use_lowercase(&config)) {
+    let json = match serde_json::to_string(&use_lowercase(config.clone())) {
         Ok(json) if json.len() <= MAX_JSON_SIZE => json,
         Ok(_) => {
             let message = "Configuration size exceeds maximum allowed size";
@@ -173,7 +173,7 @@ fn eval_script(script: &str, config_json: &str, name: &String) -> EvalOutcome {
     }
 
     match parse_json_safely(&result) {
-        Ok(config) => (Ok(use_lowercase_owned(config)), outputs.lock().to_vec()),
+        Ok(config) => (Ok(use_lowercase(config)), outputs.lock().to_vec()),
         Err(err) => {
             logging!(
                 error,