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/schemas.ts

@@ -1319,6 +1319,12 @@ export const SCHEMAS: Record<string, unknown> = {
       },
       "sniffing": {},
       "streamSettings": {},
+      "subSortIndex": {
+        "description": "1-based sort order of this inbound's links in subscription output only (lower first; ties by id)",
+        "example": 1,
+        "minimum": 1,
+        "type": "integer"
+      },
       "tag": {
         "example": "in-443-tcp",
         "type": "string"
@@ -1359,6 +1365,7 @@ export const SCHEMAS: Record<string, unknown> = {
       "shareAddrStrategy",
       "sniffing",
       "streamSettings",
+      "subSortIndex",
       "tag",
       "total",
       "trafficReset",