feat(backend): implement REST API for races calendar

Express + TypeScript backend with PostgreSQL: CRUD endpoints for /races (GET list with year/month filters, GET by id, POST, PATCH, DELETE), health/readiness probes, SQL migration runner, seed script with upsert from CSV, camelCase/snake_case mapper, CORS, env validation, docker-compose, and API docs for frontend.

Made-with: Cursor

docker-compose.yml

@@ -0,0 +1,17 @@
+version: "3.9"
+
+services:
+  postgres:
+    image: postgres:16-alpine
+    restart: unless-stopped
+    ports:
+      - "${DB_PORT:-5432}:5432"
+    environment:
+      POSTGRES_DB: ${DB_NAME:-calendar_run}
+      POSTGRES_USER: ${DB_USER:-calendar_user}
+      POSTGRES_PASSWORD: ${DB_PASSWORD:-calendar_pass}
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+
+volumes:
+  pgdata: