fix(dns): save the DNS override decision on every runtime replacement

Refs #8431

src-tauri/src/config/dns.rs

@@ -6,6 +6,7 @@ use serde_yaml_ng::{Mapping, Value};
 use sha2::{Digest as _, Sha256};
 use smartstring::alias::String;
 use std::sync::atomic::{AtomicBool, Ordering};
+use tokio::sync::MutexGuard;
 
 use super::{Config, IVerge};
 use crate::core::handle::Handle;
@@ -128,7 +129,12 @@ impl IVerge {
 
 impl Config {
     pub(crate) async fn sync_dns_override() -> Result<()> {
-        let _config_write = Self::lock_config_write().await;
+        let config_write = Self::lock_config_write().await;
+        Self::sync_dns_override_locked(&config_write).await
+    }
+
+    /// Callers must have ended their own draft transaction, which claims the same Verge layer.
+    pub(crate) async fn sync_dns_override_locked(_config_write: &MutexGuard<'_, ()>) -> Result<()> {
         let state = Self::runtime().await.data_arc().dns_override.clone();
         let Some(state) = state else {
             return Ok(());