feat: add custom file name support for saved files and improve error messages

types/model.go

@@ -7,8 +7,8 @@ import (
 type ReceivedFile struct {
 	gorm.Model
 	Processing     bool
-	ChatID         int64
-	MessageID      int
+	ChatID         int64 `gorm:"uniqueIndex:idx_chat_id_message_id;not null"`
+	MessageID      int   `gorm:"uniqueIndex:idx_chat_id_message_id;not null"`
 	ReplyMessageID int
 	FileName       string
 }