chore: consolidate local integration changes

backend/internal/domain/system_setting.go

@@ -0,0 +1,11 @@
+package domain
+
+import "time"
+
+// SystemSetting stores small global configuration documents.
+type SystemSetting struct {
+	Key       string  `gorm:"primaryKey;size:128" json:"key"`
+	Value     JSONMap `gorm:"type:jsonb" json:"value"`
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}