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/generated/examples.ts

@@ -292,6 +292,7 @@ export const EXAMPLES: Record<string, unknown> = {
     "shareAddrStrategy": "node",
     "sniffing": null,
     "streamSettings": null,
+    "subSortIndex": 1,
     "tag": "in-443-tcp",
     "total": 0,
     "trafficReset": "never",