Update docs for Docker-on-deimos deployment, add grpc_plain_addr option
- ARCHITECTURE.md: document nginx + direct gRPC topology, add
grpc_plain_addr config, update cert filenames to Let's Encrypt
convention, add passwd to CLI table
- RUNBOOK.md: replace systemctl/journalctl with docker commands,
fix cert path references, improve sync troubleshooting steps
- Example config: update cert paths, document grpc_plain_addr option
- grpcserver: add optional plaintext gRPC listener for reverse proxy
- config: add GRPCPlainAddr field
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>