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

backend/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "calendar-run-backend",
+  "version": "1.0.0",
+  "private": true,
+  "scripts": {
+    "build": "tsc",
+    "dev": "ts-node src/index.ts",
+    "start": "node dist/index.js",
+    "db:migrate": "ts-node src/migrate.ts",
+    "seed": "ts-node src/seed.ts"
+  },
+  "dependencies": {
+    "cors": "^2.8.5",
+    "csv-parse": "^5.6.0",
+    "dotenv": "^16.4.7",
+    "express": "^4.21.2",
+    "pg": "^8.13.1"
+  },
+  "devDependencies": {
+    "@types/cors": "^2.8.17",
+    "@types/express": "^5.0.0",
+    "@types/node": "^22.12.0",
+    "@types/pg": "^8.11.10",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.7.3"
+  }
+}