refactor: shorten model and table prefixes

backend/internal/models/task.go

@@ -2,7 +2,7 @@ package models
 
 import "time"
 
-type SenlinAgentTask struct {
+type SaTask struct {
 	ID                      uint    `gorm:"primaryKey"`
 	Identity                string  `gorm:"type:char(36);uniqueIndex"`
 	ProjectID               uint    `gorm:"index;not null"`
@@ -24,6 +24,6 @@ type SenlinAgentTask struct {
 	UpdatedAt               time.Time
 }
 
-func (SenlinAgentTask) TableName() string {
-	return "senlin_agent_tasks"
+func (SaTask) TableName() string {
+	return "sa_tasks"
 }