feat(server): CreateBatch/生成器切换到 codes 库(Mint 单事务全成或全无)(#codes-lib)

Store 挂库 store(NewStore 内部构造 libcodes.Store,签名不变);
generator.go 三函数委托 libcodes,ErrDuplicate 别名同一哨兵;
Service.CreateBatch 走 libcodes.Mint(签名不变)。openMigratedSQLite
挪到共享 sqlite_helper_test.go,backfill_test.go/service_sqlite_test.go
共用。Store.CreateBatch/CreateCode/CodeExistsByHash 原样保留供
webhook.go(Task 6 改用新原语,Task 7 删除)。

server/internal/codes/sqlite_helper_test.go

@@ -0,0 +1,30 @@
+package codes_test
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+
+	"github.com/wangjia/pangolin/server/internal/config"
+	"github.com/wangjia/pangolin/server/internal/store"
+)
+
+// openMigratedSQLite opens an in-memory sqlite DB, runs pangolin's full
+// golang-migrate chain (000001-000020) followed by the shared codes
+// library's own migrations. Shared by backfill_test.go and
+// service_sqlite_test.go.
+func openMigratedSQLite(t *testing.T) *sql.DB {
+	t.Helper()
+	db, err := store.Open(&config.Config{Driver: "sqlite", DSN: ":memory:"})
+	if err != nil {
+		t.Fatalf("open: %v", err)
+	}
+	t.Cleanup(func() { _ = db.Close() })
+	if err := store.MigrateUp(db, "sqlite"); err != nil {
+		t.Fatalf("migrate: %v", err)
+	}
+	if err := store.ApplyCodesLibMigrations(context.Background(), db, "sqlite"); err != nil {
+		t.Fatalf("lib migrate: %v", err)
+	}
+	return db
+}