fix(tasks): canonicalize triggered_by so execution labels resolve

Unknown values such as http and inproc_cron made the admin UI call
t(undefined). Dispatch sites now write system/manual/retry/schedule,
the list API maps legacy rows, and the table skips missing i18n keys.

backend/plugins/drivers/driver_asynq_worker/executor.go

@@ -4,6 +4,7 @@
 package driver_asynq_worker
 
 import (
+	"Wavelet/core/contracts"
 	"Wavelet/pkg/idgen"
 	"Wavelet/pkg/logger"
 	"Wavelet/pkg/util"
@@ -208,7 +209,7 @@ func RetryTask(ctx context.Context, id uint64) (string, error) {
 		MaxRetry:    execution.MaxRetry,
 		RetryCount:  execution.RetryCount + 1,
 		Payload:     execution.Payload,
-		TriggeredBy: "retry",
+		TriggeredBy: contracts.TaskTriggerRetry,
 	}
 
 	if err := createTaskExecution(ctx, newExecution); err != nil {
@@ -393,7 +394,7 @@ func getOrCreateTaskExecution(ctx context.Context, taskID string, t *asynq.Task,
 		MaxRetry:    meta.MaxRetry,
 		RetryCount:  0,
 		Payload:     string(payload),
-		TriggeredBy: "schedule",
+		TriggeredBy: contracts.TaskTriggerSchedule,
 		StartedAt:   &now,
 	}
 

backend/plugins/drivers/driver_inproc_cron/scheduler.go

@@ -99,7 +99,7 @@ func (s *inprocScheduler) registerJob(ctx context.Context, def extpoints.Schedul
 
 	_, err := s.cronRunner.AddFunc(cronSpec, func() {
 		if s.taskSvc != nil {
-			if _, dispatchErr := s.taskSvc.Dispatch(ctx, taskType, payloadBytes, "inproc_cron"); dispatchErr != nil {
+			if _, dispatchErr := s.taskSvc.Dispatch(ctx, taskType, payloadBytes, contracts.TaskTriggerSchedule); dispatchErr != nil {
 				logger.ErrorF(ctx, "driver_inproc_cron: dispatch task %q failed: %v", taskType, dispatchErr)
 			}
 			return

backend/plugins/drivers/driver_inproc_worker/executor.go

@@ -76,7 +76,7 @@ func (q *InprocQueue) Enqueue(ctx context.Context, taskType string, payload []by
 	}
 
 	if source == "" {
-		source = "manual"
+		source = contracts.TaskTriggerManual
 	}
 	idType := td.Type
 	if idType == "" {