refactor backend packages and global db service

backend/internal/models/ai_session.go

@@ -0,0 +1,17 @@
+package models
+
+import "time"
+
+type SenlinAgentAISession struct {
+	ID        uint   `gorm:"primaryKey"`
+	ProjectID uint   `gorm:"index;not null"`
+	CreatedBy uint   `gorm:"index;not null"`
+	Title     string `gorm:"not null"`
+	Context   string `gorm:"type:text"`
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func (SenlinAgentAISession) TableName() string {
+	return "senlin_agent_ai_sessions"
+}