feat: backend service

pkg/model/user/user.go

@@ -80,6 +80,13 @@ type EntitlementSnapshot struct {
 
 	// UpdatedAt stores when the snapshot was last recomputed.
 	UpdatedAt time.Time `json:"updated_at"`
+
+	// MaxRegisteredRaceNames mirrors the per-tier quota carried in the
+	// backend HTTP response (`backend.EntitlementSnapshot`). Gateway
+	// re-validates the response shape with strict-unknown-field
+	// decoding, so the field must be present here even when the
+	// FlatBuffers schema does not yet carry it.
+	MaxRegisteredRaceNames int32 `json:"max_registered_race_names"`
 }
 
 // ActiveSanction stores one transport-ready active sanction returned in the