refactor(documents): split document models

backend/internal/models/document_content.go

@@ -0,0 +1,15 @@
+package models
+
+import "time"
+
+type SaDocumentContent struct {
+	ID         uint   `gorm:"primaryKey"`
+	DocumentID uint   `gorm:"uniqueIndex;not null"`
+	Markdown   string `gorm:"type:text"`
+	CreatedAt  time.Time
+	UpdatedAt  time.Time
+}
+
+func (SaDocumentContent) TableName() string {
+	return "sa_document_contents"
+}