fix(database): make cross-db migration lossless, transactional, and pre-checked

migrationModels was missing ClientGroup and ClientGlobalTraffic, so both
migration directions silently dropped client groups and global client
traffic; the model list is now extracted to allModels and a parity test
keeps the two lists from drifting again. MigrateData runs its truncate
and copy inside one transaction so a failed import rolls back instead of
leaving the destination truncated (sequences resync after commit since
setval is non-transactional). New PrepareSQLiteForMigration rejects
uploads that are not a panel database and AutoMigrates old backups so
their missing tables cannot break the row copy.

internal/database/prepare_sqlite_test.go

@@ -0,0 +1,66 @@
+package database
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/mhsanaei/3x-ui/v3/internal/database/model"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+func TestPrepareSQLiteForMigration(t *testing.T) {
+	t.Run("rejects non-panel database", func(t *testing.T) {
+		dbPath := filepath.Join(t.TempDir(), "random.db")
+		gdb, err := gorm.Open(sqlite.Open(dbPath), &gorm.Config{Logger: logger.Discard})
+		if err != nil {
+			t.Fatalf("open sqlite: %v", err)
+		}
+		if err := gdb.Exec("CREATE TABLE notes(id integer primary key, body text)").Error; err != nil {
+			t.Fatalf("create table: %v", err)
+		}
+		closeGorm(gdb)
+
+		err = PrepareSQLiteForMigration(dbPath)
+		if err == nil {
+			t.Fatal("PrepareSQLiteForMigration accepted a non-panel database, want error")
+		}
+		if !strings.Contains(err.Error(), "not a 3x-ui panel database") {
+			t.Fatalf("error = %q, want it to contain %q", err.Error(), "not a 3x-ui panel database")
+		}
+	})
+
+	t.Run("upgrades old panel schema", func(t *testing.T) {
+		dbPath := filepath.Join(t.TempDir(), "old.db")
+		gdb, err := gorm.Open(sqlite.Open(dbPath), &gorm.Config{Logger: logger.Discard})
+		if err != nil {
+			t.Fatalf("open sqlite: %v", err)
+		}
+		if err := gdb.AutoMigrate(&model.User{}, &model.Setting{}, &model.Inbound{}); err != nil {
+			t.Fatalf("automigrate legacy subset: %v", err)
+		}
+		closeGorm(gdb)
+
+		if err := PrepareSQLiteForMigration(dbPath); err != nil {
+			t.Fatalf("PrepareSQLiteForMigration rejected an old panel database: %v", err)
+		}
+
+		check, err := gorm.Open(sqlite.Open(dbPath), &gorm.Config{Logger: logger.Discard})
+		if err != nil {
+			t.Fatalf("reopen sqlite: %v", err)
+		}
+		defer closeGorm(check)
+		sqlDB, err := check.DB()
+		if err != nil {
+			t.Fatalf("sql db: %v", err)
+		}
+		for _, table := range []string{"client_groups", "client_global_traffics", "outbound_subscriptions"} {
+			if !sqliteTableExists(sqlDB, table) {
+				t.Errorf("table %s was not created by the schema upgrade", table)
+			}
+		}
+	})
+}