fix: resolve remaining gofmt alignment and deprecated API issues

- Fix struct tag alignment in dto/types.go (AffinityClientCount)
- Fix struct literal alignment in sora_generation_service.go
- Replace deprecated google.CredentialsFromJSONWithParams with
  option.WithCredentialsJSON for service account auth (SA1019)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/internal/handler/dto/types.go

@@ -193,7 +193,7 @@ type Account struct {
 	ClientAffinityEnabled *bool `json:"client_affinity_enabled,omitempty"`
 
 	// 亲和客户端数据（仅 admin 列表端点注入，不由 mapper 填充）
-	AffinityClientCount *int64    `json:"affinity_client_count,omitempty"`
+	AffinityClientCount *int64   `json:"affinity_client_count,omitempty"`
 	AffinityClients     []string `json:"affinity_clients,omitempty"`
 
 	// API Key 账号配额限制

backend/internal/service/sora_gdrive_storage.go

@@ -153,13 +153,7 @@ func (s *SoraGDriveStorage) buildOAuth2Service(ctx context.Context, profile *Sor
 }
 
 func (s *SoraGDriveStorage) buildServiceAccountService(ctx context.Context, profile *SoraS3Profile) (*drive.Service, error) {
-	creds, err := google.CredentialsFromJSONWithParams(ctx, []byte(profile.ServiceAccountJSON), google.CredentialsParams{
-		Scopes: []string{drive.DriveFileScope},
-	})
-	if err != nil {
-		return nil, fmt.Errorf("parse service account json: %w", err)
-	}
-	srv, err := drive.NewService(ctx, option.WithCredentials(creds))
+	srv, err := drive.NewService(ctx, option.WithCredentialsJSON([]byte(profile.ServiceAccountJSON)))
 	if err != nil {
 		return nil, fmt.Errorf("create gdrive service account service: %w", err)
 	}

backend/internal/service/sora_generation_service.go

@@ -47,9 +47,9 @@ func NewSoraGenerationService(
 	quotaService *SoraQuotaService,
 ) *SoraGenerationService {
 	return &SoraGenerationService{
-		genRepo:        genRepo,
-		objectStorage:  objectStorage,
-		quotaService:   quotaService,
+		genRepo:       genRepo,
+		objectStorage: objectStorage,
+		quotaService:  quotaService,
 	}
 }