feat(clients): bind host rules to individual clients in subscriptions (#6620)

Host rules applied per inbound only, so every client of an inbound got the same
subscription endpoints (#6618). A client can now be bound to one or more host
rules, and its raw, JSON and Clash subscriptions render only those hosts, in
either subscription order; an unbound client is unchanged. A binding whose hosts
are deleted, disabled or excluded from the format fails closed: the client gets
no links there but stays in traffic accounting. Host edits keep row ids, so
bindings survive them; nil leaves a stored binding alone and an empty list
clears it.

internal/web/service/client_host_binding_test.go

@@ -0,0 +1,64 @@
+package service
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/database"
+	"github.com/mhsanaei/3x-ui/v3/internal/database/dbtest"
+	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
+)
+
+func setupHostBindingDB(t *testing.T) {
+	t.Helper()
+	dbDir := t.TempDir()
+	t.Setenv("XUI_DB_FOLDER", dbDir)
+	dbtest.InitDB(t, filepath.Join(dbDir, "x-ui.db"))
+}
+
+func TestUpdate_OmittedPreservesAndEmptyClearsHostBindings(t *testing.T) {
+	setupHostBindingDB(t)
+	svc := &ClientService{}
+	inboundSvc := &InboundService{}
+
+	rec := &model.ClientRecord{
+		Email:             "hostbind@x",
+		UUID:              "11111111-1111-1111-1111-111111111111",
+		SubID:             "hostbind@x",
+		Enable:            true,
+		ClientHostRuleIds: []int{7},
+	}
+	if err := database.GetDB().Create(rec).Error; err != nil {
+		t.Fatalf("create record: %v", err)
+	}
+
+	omitted := rec.ToClient()
+	omitted.ClientHostRuleIds = nil
+	omitted.Comment = "touch"
+	if _, err := svc.Update(inboundSvc, rec.Id, *omitted, 0); err != nil {
+		t.Fatalf("Update omitted: %v", err)
+	}
+	got, err := svc.GetByID(rec.Id)
+	if err != nil {
+		t.Fatalf("GetByID: %v", err)
+	}
+	if got.ClientHostRuleIds == nil || len(got.ClientHostRuleIds) != 1 || got.ClientHostRuleIds[0] != 7 {
+		t.Fatalf("omitted must preserve list, got %v", got.ClientHostRuleIds)
+	}
+
+	cleared := got.ToClient()
+	cleared.ClientHostRuleIds = []int{}
+	if _, err := svc.Update(inboundSvc, rec.Id, *cleared, 0); err != nil {
+		t.Fatalf("Update clear: %v", err)
+	}
+	after, err := svc.GetByID(rec.Id)
+	if err != nil {
+		t.Fatalf("GetByID: %v", err)
+	}
+	if after.ClientHostRuleIds == nil {
+		t.Fatalf("empty must clear to non-nil empty, got nil")
+	}
+	if len(after.ClientHostRuleIds) != 0 {
+		t.Fatalf("empty must clear list, got %v", after.ClientHostRuleIds)
+	}
+}