Revert "autoresearch iter 28: CORDIS gate contracts must not carry table names"

This reverts commit 2cb8d9a892.

backend/core/contracts/auth.go

@@ -29,6 +29,11 @@ type UserDTO struct {
 	UpdatedAt          time.Time `json:"updated_at"`
 }
 
+// TableName returns w_users.
+func (UserDTO) TableName() string {
+	return "w_users"
+}
+
 // OAuthUserInfoDTO contains user identity claims obtained from an OAuth provider.
 type OAuthUserInfoDTO struct {
 	ID                uint64 `json:"id"`