MANTIS_API_KEY_PEPPER as a required secret. Generate it
with openssl rand -base64 32 when Render prompts for the value, and keep it
stable for the life of the database.
Free tier spins down after 15 min idle → first mantis trigger after idle takes 30–60s. For real mantis use, upgrade to Starter ($7/mo) or use Railway/Fly.
For app-layer URL/rate limits, use a Cloudflare-proxied custom domain; see edge limits.