fix(core): upgrade mihomo atomically instead of letting it self-update

mihomo's updater truncates its own running executable in place; macOS kills
that under Hardened Runtime and leaves a 0-byte core. Verge now downloads the
release, verifies a staged copy next to the target, and renames it into place,
which never touches the inode the running core executes from.

Closes #6834

src-tauri/src/cmd/clash.rs

@@ -118,6 +118,16 @@ pub async fn restart_core() -> CmdResult {
     result
 }
 
+/// Replaces the managed core binary atomically instead of letting mihomo overwrite itself.
+#[tauri::command]
+pub async fn upgrade_clash_core(force: bool) -> CmdResult<feat::CoreUpgradeReport> {
+    let report = feat::upgrade_core(force).await.with_error_code("CORE_UPGRADE_FAILED")?;
+    if report.upgraded {
+        handle::Handle::refresh_clash();
+    }
+    Ok(report)
+}
+
 #[tauri::command]
 pub async fn test_delay(url: String) -> CmdResult<u32> {
     let result = match feat::test_delay(url).await {