feat(hosts): add drag-and-drop and global subscription ordering (#6895)

Hosts already had one saved order on the Hosts page, but subscriptions honoured
it only inside each inbound, so a host of a later inbound could never come before
one of an earlier inbound (#6894). A new opt-in setting makes raw/base64,
Clash/Mihomo and JSON subscriptions follow the Hosts page order across inbounds;
the default keeps today's inbound-first output unchanged. The Hosts table gains
drag-and-drop reordering next to the Up/Down buttons, on a pointer-reorder hook
the Routing Rules table now shares.

internal/sub/json_service.go

@@ -136,6 +136,7 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 
 	seenEmails := make(map[string]struct{})
 	entries := make([]subConfigEntry, 0, len(inbounds))
+	var ordered []orderedSubEntry[func() subConfigEntry]
 	// Prepare Inbounds
 	for _, inbound := range inbounds {
 		clients := subReq.matchingClients(inbound, subId)
@@ -149,8 +150,10 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 			continue
 		}
 		subReq.projectThroughFallbackMaster(inbound)
-		if hostEps := subReq.hostEndpoints(inbound, "json"); len(hostEps) > 0 {
-			injectExternalProxy(inbound, hostEps)
+		if !subReq.hostsFirst {
+			if hostEps := subReq.hostEndpoints(inbound, "json"); len(hostEps) > 0 {
+				injectExternalProxy(inbound, hostEps)
+			}
 		}
 
 		var inboundConfigs []json_util.RawMessage
@@ -159,7 +162,17 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 				hasEnabledClient = true
 			}
 			seenEmails[client.Email] = struct{}{}
-			inboundConfigs = append(inboundConfigs, s.getConfig(subReq, inbound, client, host)...)
+			if subReq.hostsFirst {
+				for _, variant := range subReq.subscriptionHostVariants(inbound, "json") {
+					render := func() subConfigEntry {
+						configs := s.getConfig(subReq, variant.inbound(subReq, inbound), client, host)
+						return subConfigEntry{sortIndex: inbound.SubSortIndex, id: inbound.Id, configs: configs, hostOrder: variant.order}
+					}
+					ordered = append(ordered, orderedSubEntry[func() subConfigEntry]{variant.order, render})
+				}
+			} else {
+				inboundConfigs = append(inboundConfigs, s.getConfig(subReq, inbound, client, host)...)
+			}
 		}
 		if len(inboundConfigs) > 0 {
 			entries = append(entries, subConfigEntry{
@@ -169,6 +182,14 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 			})
 		}
 	}
+	if subReq.hostsFirst {
+		// Render in final endpoint order so first-link usage remarks stay first.
+		for _, render := range orderedSubValues(ordered) {
+			if entry := render(); len(entry.configs) > 0 {
+				entries = append(entries, entry)
+			}
+		}
+	}
 	entries = s.appendBalancerEntries(entries)
 
 	// Inbounds arrive sorted by (sub_sort_index, id); balancers interleave by
@@ -183,6 +204,23 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 		return entries[i].id < entries[j].id
 	})
 	var configArray []json_util.RawMessage
+	if subReq.hostsFirst {
+		// Preserve balancer slots from the legacy sort; reorder endpoint slots only.
+		var endpoints []subConfigEntry
+		for _, entry := range entries {
+			if entry.kind == 0 {
+				endpoints = append(endpoints, entry)
+			}
+		}
+		sort.SliceStable(endpoints, func(i, j int) bool { return hostOrderLess(endpoints[i].hostOrder, endpoints[j].hostOrder) })
+		next := 0
+		for i := range entries {
+			if entries[i].kind == 0 {
+				entries[i] = endpoints[next]
+				next++
+			}
+		}
+	}
 	for _, entry := range entries {
 		configArray = append(configArray, entry.configs...)
 	}
@@ -255,6 +293,7 @@ func (s *SubJsonService) GetJson(subId string, host string, alwaysReturnArray bo
 // subConfigEntry is one ordered block of the JSON subscription: an inbound's
 // configs (kind 0) or a balancer config (kind 1).
 type subConfigEntry struct {
+	hostOrder *hostEntryOrder
 	sortIndex int
 	kind      int
 	id        int