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/lib/xray/inbound-form-adapter.ts

@@ -39,6 +39,7 @@ export interface RawInboundRow {
   nodeId?: number | null;
   shareAddrStrategy?: string;
   shareAddr?: string;
+  subSortIndex?: number;
   clientStats?: unknown;
 }
 
@@ -65,6 +66,7 @@ export interface WireInboundPayload {
   nodeId?: number;
   shareAddrStrategy: ShareAddrStrategy;
   shareAddr: string;
+  subSortIndex: number;
 }
 
 function coerceJsonObject(value: unknown): Record<string, unknown> {
@@ -175,6 +177,7 @@ export function rawInboundToFormValues(row: RawInboundRow): InboundFormValues {
     nodeId: row.nodeId ?? null,
     shareAddrStrategy: coerceShareAddrStrategy(row.shareAddrStrategy),
     shareAddr: row.shareAddr ?? '',
+    subSortIndex: Math.max(1, row.subSortIndex ?? 1),
     protocol,
     settings,
   } as InboundFormValues;
@@ -322,6 +325,7 @@ export function formValuesToWirePayload(values: InboundFormValues): WireInboundP
     tag: values.tag,
     shareAddrStrategy: values.shareAddrStrategy,
     shareAddr: values.shareAddr,
+    subSortIndex: values.subSortIndex,
   };
   if (values.nodeId != null) payload.nodeId = values.nodeId;
   return payload;