validate-env.js now reads all four required vars (MONGODB_URI, JWT_SECRET,
RESEND_API_KEY, HELCIM_API_TOKEN) from useRuntimeConfig() instead of mixing
direct process.env reads with a JWT-only special case. Mongoose and the six
Resend instantiations follow suit. Either bare or NUXT_-prefixed env names
are accepted, so Dokploy no longer needs duplicate entries.