feat: add registration and authentication

backend/src/mappers/race.ts

@@ -4,6 +4,8 @@
  */
 export interface RaceRow {
   id: string;
+  slug: string;
+  owner_user_id: string | null;
   race_date: string | Date;
   title: string;
   distance_km: string;
@@ -24,6 +26,7 @@ export interface RaceRow {
 /** API shape (camelCase). */
 export interface RaceDto {
   id: string;
+  slug: string;
   date: string;
   title: string;
   distanceKm: number;
@@ -61,6 +64,7 @@ function raceDateToApiValue(value: string | Date): string {
 export function rowToDto(row: RaceRow): RaceDto {
   return {
     id: row.id,
+    slug: row.slug,
     date: raceDateToApiValue(row.race_date),
     title: row.title,
     distanceKm: parseFloat(row.distance_km),
@@ -81,6 +85,7 @@ export function rowToDto(row: RaceRow): RaceDto {
 
 /** Map incoming camelCase body fields to snake_case column names. */
 const FIELD_MAP: Record<string, string> = {
+  slug: "slug",
   date: "race_date",
   title: "title",
   distanceKm: "distance_km",