feat(schedule): support KOL subscription targets and random time windows

Extend schedule tasks to dispatch KOL subscription prompts in addition
to prompt rules, add daily/weekly scheduling with fixed or random time
windows, and track dispatch outcomes (last run, status, consecutive
failures).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/tenant/transport/schedule_task_handler.go

@@ -39,6 +39,14 @@ func (h *ScheduleTaskHandler) List(c *gin.Context) {
 			params.PromptRuleID = &rid
 		}
 	}
+	if v := c.Query("subscription_prompt_id"); v != "" {
+		if rid, err := strconv.ParseInt(v, 10, 64); err == nil {
+			params.SubscriptionPromptID = &rid
+		}
+	}
+	if v := c.Query("target_type"); v != "" {
+		params.TargetType = &v
+	}
 	if v := c.Query("status"); v != "" {
 		params.Status = &v
 	}