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/src/config.ts

@@ -0,0 +1,24 @@
+import path from "path";
+import dotenv from "dotenv";
+
+dotenv.config({ path: path.resolve(__dirname, "../../.env") });
+
+function requireEnv(name: string): string {
+  const value = process.env[name];
+  if (!value) {
+    throw new Error(`Missing required environment variable: ${name}`);
+  }
+  return value;
+}
+
+export const config = {
+  db: {
+    host: requireEnv("DB_HOST"),
+    port: parseInt(requireEnv("DB_PORT"), 10),
+    database: requireEnv("DB_NAME"),
+    user: requireEnv("DB_USER"),
+    password: requireEnv("DB_PASSWORD"),
+  },
+  apiPort: parseInt(process.env.API_PORT || "3001", 10),
+  corsOrigin: process.env.CORS_ORIGIN || "http://localhost:5173",
+};