feat(xray): default outbound in basic routing (#5815)

* feat(xray): default outbound picker in basic routing

Let panel users choose which outbound handles unmatched traffic by
moving it to the first position in the template outbounds list.

* fix(xray): keep direct/blocked outbounds when changing default

* style(routing): revert incidental whitespace churn

Drop double blank lines and the reformatted function signature so the default-outbound diff stays focused on behavior.

frontend/src/pages/xray/basics/helpers.ts

@@ -1,4 +1,5 @@
 import type { XraySettingsValue } from '@/hooks/useXraySetting';
+import { blockedSettings, directSettings } from './constants';
 
 export function ruleGetter(t: XraySettingsValue | null, outboundTag: string, property: string): string[] {
   if (!t?.routing?.rules) return [];
@@ -55,6 +56,28 @@ export function syncOutbound(t: XraySettingsValue, tag: string, settings: Record
   if (haveRules && idx < 0) t.outbounds.push(settings as never);
 }
 
+export function getDefaultOutboundTag(t: XraySettingsValue | null): string {
+  const tag = t?.outbounds?.[0]?.tag;
+  return typeof tag === 'string' && tag.length > 0 ? tag : 'direct';
+}
+
+export function setDefaultOutboundTag(t: XraySettingsValue, tag: string): void {
+  if (!tag) return;
+  if (!Array.isArray(t.outbounds)) t.outbounds = [];
+  const idx = t.outbounds.findIndex((o) => o?.tag === tag);
+  if (idx < 0) {
+    if (tag === 'direct') t.outbounds.push(directSettings as never);
+    else if (tag === 'blocked') t.outbounds.push(blockedSettings as never);
+    else return;
+    const newIdx = t.outbounds.length - 1;
+    const [moved] = t.outbounds.splice(newIdx, 1);
+    t.outbounds.unshift(moved);
+  } else if (idx > 0) {
+    const [moved] = t.outbounds.splice(idx, 1);
+    t.outbounds.unshift(moved);
+  }
+}
+
 export function propagateOutboundTagRename(
   t: XraySettingsValue,
   oldTag: string,