refactor: shorten model and table prefixes

backend/internal/models/task_share.go

@@ -2,7 +2,7 @@ package models
 
 import "time"
 
-type SenlinAgentTaskShare struct {
+type SaTaskShare struct {
 	ID             uint   `gorm:"primaryKey"`
 	Identity       string `gorm:"type:char(36);uniqueIndex"`
 	TaskID         uint   `gorm:"index;not null"`
@@ -13,6 +13,6 @@ type SenlinAgentTaskShare struct {
 	CreatedAt      time.Time
 }
 
-func (SenlinAgentTaskShare) TableName() string {
-	return "senlin_agent_task_shares"
+func (SaTaskShare) TableName() string {
+	return "sa_task_shares"
 }