feat(sub): per-inbound sort order for subscription links

Add a subSortIndex field to inbounds that controls the order of links
in subscription output only: the raw sub body, the HTML sub page, and
the JSON/Clash formats (all served from the same query). Lower values
come first; ties keep id order. The panel inbound list is unaffected.

The value is editable in the inbound form next to the share-address
fields, propagates to nodes via wireInbound, and follows the usual
node-sync rules (copied on import, mirrored while not dirty, never a
structural change).

Rescoped from #5214 by @Ponywka.

frontend/src/pages/inbounds/list/InboundList.tsx

@@ -93,6 +93,11 @@ export default function InboundList({
     [dbInbounds],
   );
 
+  const hasAnySubSortIndex = useMemo(
+    () => dbInbounds.some((i) => (i.subSortIndex ?? 1) > 1),
+    [dbInbounds],
+  );
+
   const toggleSelect = useCallback((id: number, checked: boolean) => {
     setSelectedRowKeys((prev) => {
       const next = new Set(prev);
@@ -115,6 +120,7 @@ export default function InboundList({
 
   const columns = useInboundColumns({
     hasAnyRemark,
+    hasAnySubSortIndex,
     hasActiveNode,
     nodesById,
     clientCount,