feat(db): purchase_task 新增 created_by/created_source 迁移 (#382)

只新增可空 created_by（索引）与非空默认空串的 created_source，不回填历史行；
迁移按列/索引存在性守卫，可重复执行。

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NTDbDcwbDw1TSAcE6wfh2F

server/app/goauto/models/purchase.go

@@ -170,8 +170,13 @@ type PurchaseTask struct {
 	CancelReason             *string    `json:"cancelReason" gorm:"size:500"`
 	ErrorCode                *string    `json:"errorCode" gorm:"size:64;index"`
 	ErrorMessage             *string    `json:"errorMessage" gorm:"size:1000"`
-	CreatedAt                time.Time  `json:"createdAt"`
-	UpdatedAt                time.Time  `json:"updatedAt"`
+	// CreatedBy/CreatedSource 只在新建任务时写入一次（#382）：admin=管理端账号，
+	// client_api=客户端密钥的授权人，agent=设备重试（CreatedBy 为空）；空串表示
+	// 迁移前的历史任务，不回填。
+	CreatedBy     *uint64   `json:"createdBy" gorm:"index"`
+	CreatedSource string    `json:"createdSource" gorm:"size:16;not null;default:''"`
+	CreatedAt     time.Time `json:"createdAt"`
+	UpdatedAt     time.Time `json:"updatedAt"`
 }
 
 func (PurchaseTask) TableName() string { return "purchase_task" }

server/cmd/migrate/migration/version-local/1791700000000_purchase_task_creator.go

@@ -0,0 +1,37 @@
+package version_local
+
+import (
+	"runtime"
+
+	"go-admin/app/goauto/models"
+	"go-admin/cmd/migrate/migration"
+	common "go-admin/common/models"
+
+	"gorm.io/gorm"
+)
+
+func init() {
+	_, file, _, _ := runtime.Caller(0)
+	migration.Migrate.SetVersion(migration.GetFilename(file), MigratePurchaseTaskCreator)
+}
+
+// MigratePurchaseTaskCreator only adds the #382 creator columns to
+// purchase_task: nullable created_by (indexed) and created_source defaulting
+// to the empty string. Existing rows are not rewritten or backfilled. Each step is guarded so
+// a partial run (MySQL DDL commits implicitly) can be re-run safely.
+func MigratePurchaseTaskCreator(db *gorm.DB, version string) error {
+	m := db.Migrator()
+	for _, column := range []string{"CreatedBy", "CreatedSource"} {
+		if !m.HasColumn(&models.PurchaseTask{}, column) {
+			if err := m.AddColumn(&models.PurchaseTask{}, column); err != nil {
+				return err
+			}
+		}
+	}
+	if !m.HasIndex(&models.PurchaseTask{}, "idx_purchase_task_created_by") {
+		if err := m.CreateIndex(&models.PurchaseTask{}, "CreatedBy"); err != nil {
+			return err
+		}
+	}
+	return db.Where("version = ?", version).FirstOrCreate(&common.Migration{Version: version}).Error
+}

server/cmd/migrate/migration/version-local/1791700000000_purchase_task_creator_test.go

@@ -0,0 +1,59 @@
+package version_local
+
+import (
+	"testing"
+
+	"go-admin/app/goauto/models"
+	common "go-admin/common/models"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+func TestMigratePurchaseTaskCreatorAddsColumnsKeepsLegacyRowsAndIsIdempotent(t *testing.T) {
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{Logger: logger.Default.LogMode(logger.Silent)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn, _ := db.DB()
+	defer conn.Close()
+	if err = db.AutoMigrate(&common.Migration{}); err != nil {
+		t.Fatal(err)
+	}
+	if err = db.Exec("CREATE TABLE purchase_task (id integer primary key, status text NOT NULL)").Error; err != nil {
+		t.Fatal(err)
+	}
+	if err = db.Exec("INSERT INTO purchase_task(id,status) VALUES(1,'failed')").Error; err != nil {
+		t.Fatal(err)
+	}
+	for i := 0; i < 2; i++ {
+		if err = MigratePurchaseTaskCreator(db, "test_382"); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, column := range []string{"CreatedBy", "CreatedSource"} {
+		if !db.Migrator().HasColumn(&models.PurchaseTask{}, column) {
+			t.Fatalf("missing column %s", column)
+		}
+	}
+	if !db.Migrator().HasIndex(&models.PurchaseTask{}, "idx_purchase_task_created_by") {
+		t.Fatal("missing created_by index")
+	}
+	var row struct {
+		Status        string
+		CreatedBy     *uint64
+		CreatedSource string
+	}
+	if err = db.Table("purchase_task").Select("status, created_by, created_source").Where("id = 1").Scan(&row).Error; err != nil {
+		t.Fatal(err)
+	}
+	if row.Status != "failed" || row.CreatedBy != nil || row.CreatedSource != "" {
+		t.Fatalf("legacy row changed: %+v", row)
+	}
+	var count int64
+	db.Model(&common.Migration{}).Where("version = ?", "test_382").Count(&count)
+	if count != 1 {
+		t.Fatal("version not idempotent")
+	}
+}