feat: complete project workspace tags and notes UI

backend/internal/models/project.go

@@ -8,6 +8,9 @@ type SenlinAgentProject struct {
 	OwnerID       uint   `gorm:"index;not null"`
 	OwnerIdentity string `gorm:"type:char(36);index"`
 	Name          string `gorm:"not null"`
+	Identifier    string `gorm:"index"`
+	Icon          string
+	Background    string
 	Description   string
 	CreatedAt     time.Time
 	UpdatedAt     time.Time