refactor: revive cleanup — unused params to _, add missing doc comments

- admin/db_helper GetCache/GetUserService/GetAuthService: ctx -> _ (签名对称保留)
- validateMergedStorageConfig / ParseMigrationTargetConfig / MockStorageService.Put 未用参数 -> _
- SetDBServiceForTest、StorageDriver 常量组补充文档注释
lint_issues 33→26

.auto/log.jsonl

@@ -1,2 +1,3 @@
 {"ts":"2026-08-28T00:00:00Z","iter":0,"type":"baseline","metrics":{"lint_issues":45,"dup_issues":15,"tests_passed":44},"description":"baseline: 45 golangci issues (15 dupl), all tests pass","asi":{"note":"quick wins queue: gofumpt(4)+revive(8); then goconst/mnd; gosec; nilerr bug; contextcheck; dupl batches; nestif"}}
 {"ts":"2026-08-28","iter":1,"type":"keep","metrics":{"lint_issues":34,"dup_issues":15,"tests_passed":44},"delta":-11,"description":"goconst(9): taskCategoryUpload/taskQueueDefault consts in upload/task; reuse logDBNameSQLite in admin; mnd(1): defaultCleanupInterval in disk cache; staticcheck SA9004: split typed const group in asynq executor","asi":{"lesson":"golangci v2 defaults cap reporting at 50/3 - uncapped via issues:max-issues-per-linter/max-same-issues=0 (strict-only change); formatter war resolved: make format now = golangci-lint fmt (same gate as code-check), 203-file gofumpt normalization committed as infra"}}
+{"ts":"2026-08-28","iter":2,"type":"keep","metrics":{"lint_issues":33,"dup_issues":15,"tests_passed":44},"delta":-1,"description":"nilerr real bug: FlushTaskExecutionLog swallowed cache faults (non-miss errors) and silently dropped buffered task logs; now propagates wrapped error, ErrCacheMiss stays a no-op. 3 regression tests (fault / miss / persist+clear) with miniredis + stubDBService(in-memory sqlite)","asi":{"lesson":"FlushTaskExecutionLog callers in executor.go only log errors, so returning wrapped err is safe; tests need SetDBService injection since testhelper.SetupTestEnvironment targets infra/database global not admin dbService"}}

backend/core/contracts/storage.go

@@ -49,6 +49,7 @@ type IngestResult struct {
 // StorageDriver identifies a supported storage backend.
 type StorageDriver string
 
+// Storage drivers supported by the platform. Values persist in storage configs.
 const (
 	StorageDriverLocal  StorageDriver = "local"
 	StorageDriverS3     StorageDriver = "s3"

backend/plugins/domain/admin/db_helper.go

@@ -113,22 +113,25 @@ func GetDB(ctx context.Context) *gorm.DB {
 	return dbService.DB(ctx)
 }
 
-// GetCache returns the unified CacheService instance.
-func GetCache(ctx context.Context) contracts.CacheService {
+// GetCache returns the unified CacheService instance. ctx is kept for
+// signature symmetry with the other context-aware accessors.
+func GetCache(_ context.Context) contracts.CacheService {
 	servicesMu.RLock()
 	defer servicesMu.RUnlock()
 	return cacheService
 }
 
-// GetUserService returns the UserService instance.
-func GetUserService(ctx context.Context) contracts.UserService {
+// GetUserService returns the UserService instance. ctx is kept for
+// signature symmetry with the other context-aware accessors.
+func GetUserService(_ context.Context) contracts.UserService {
 	servicesMu.RLock()
 	defer servicesMu.RUnlock()
 	return userService
 }
 
-// GetAuthService returns the AuthService instance.
-func GetAuthService(ctx context.Context) contracts.AuthService {
+// GetAuthService returns the AuthService instance. ctx is kept for
+// signature symmetry with the other context-aware accessors.
+func GetAuthService(_ context.Context) contracts.AuthService {
 	servicesMu.RLock()
 	defer servicesMu.RUnlock()
 	return authService

backend/plugins/domain/admin/handlers_config.go

@@ -507,7 +507,7 @@ func validateAndMergeStorageConfig(ctx context.Context, value, currentConfig str
 	return string(unmaskedVal), nil
 }
 
-func validateMergedStorageConfig(ctx context.Context, currentCfg, newCfg, targetCfg contracts.StorageConfigDTO) error {
+func validateMergedStorageConfig(ctx context.Context, currentCfg, newCfg, _ contracts.StorageConfigDTO) error {
 	if newCfg.Driver != "" && newCfg.Driver != currentCfg.Driver {
 		var uploadCount int64
 		gormDB := GetDB(ctx)

backend/plugins/domain/message_gateway/db_helper.go

@@ -21,6 +21,7 @@ var (
 	taskSvc  contracts.TaskService
 )
 
+// SetDBServiceForTest injects a DBService for tests. Production wiring must use Apply.
 func SetDBServiceForTest(s contracts.DBService) {
 	setDBService(s)
 }

backend/plugins/domain/upload/shared/test_helpers.go

@@ -120,7 +120,7 @@ func NewMockStorageService() *MockStorageService {
 }
 
 // Put uploads an object into mock storage.
-func (m *MockStorageService) Put(_ context.Context, key string, body io.Reader, size int64, contentType string) (contracts.StoragePutResult, error) {
+func (m *MockStorageService) Put(_ context.Context, key string, body io.Reader, _ int64, contentType string) (contracts.StoragePutResult, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	data, err := io.ReadAll(body)

backend/plugins/domain/upload/storage/migration.go

@@ -36,7 +36,7 @@ func LatestMigrationExecution(ctx context.Context) (*contracts.TaskExecutionDTO,
 }
 
 // ParseMigrationTargetConfig parses and validates a storage migration target payload.
-func ParseMigrationTargetConfig(ctx context.Context, payload []byte) (contracts.StorageConfigDTO, error) {
+func ParseMigrationTargetConfig(_ context.Context, payload []byte) (contracts.StorageConfigDTO, error) {
 	if strings.TrimSpace(string(payload)) == "" {
 		return contracts.StorageConfigDTO{}, errors.New("storage migration target payload is required")
 	}