Environment configuration

When to use: Adding or reading env vars, updating .env.example, or validating config at startup with parseEnv / parseEnvOptional.

`LAT_` prefix convention

All application environment variables must be prefixed with LAT_ so they do not collide with third-party services, Docker, or common names.

Use LAT_ for:

Database URLs and pool settings (LAT_DATABASE_URL, LAT_PG_POOL_MAX, …)
Service endpoints the app reads (LAT_CLICKHOUSE_URL, LAT_REDIS_HOST, …)
App ports (LAT_API_PORT, LAT_WEB_PORT, LAT_INGEST_PORT)
Auth, email, OAuth, billing, CORS (LAT_BETTER_AUTH_SECRET, LAT_MAILPIT_HOST, …)
Any new variable consumed by Latitude application code