ops: production runbook for public testnet/mainnet

[TheNewAutonomy]

Goal

Create an operator runbook covering deployment, monitoring, upgrades, incident response, and rollback.

Scope

• Systemd/service templates
• Log/metric collection guidance
• Alerting thresholds (stall detection, peer drops, disk)
• Backup/restore and disaster recovery

Acceptance criteria

• A new operator can deploy a node from scratch following docs
• Runbook includes a troubleshooting decision tree

[TheNewAutonomy]

Related: created #218 to track HTTPS/TLS termination for RPC (Caddy/nginx templates + docs). This should be included in the production runbook.