Warn about duplicate VPS compose stacks

Summary

The live server currently has both islandflow-vps and an older islandflow compose project. The supported production traffic path uses islandflow-vps. I added a deploy-time warning and documentation updates so Docker remains the intended VPS path and the repo-root docker-compose.yml is clearly marked as local-only. I also attempted to remove the stale islandflow containers on the VPS, but Docker operations against them hung and timed out, so manual cleanup is tracked separately.

Changes Made

• Updated scripts/deploy.ts so Docker runtime prechecks warn when the server also has a compose project named islandflow.
• Updated README.md to explicitly say the repo-root docker-compose.yml is for local infra only and should not be run on the VPS.
• Updated deployment/docker/README.md with the same warning and a note about the duplicate-project detector.
• Inspected the live VPS and confirmed that Nginx Proxy Manager routes public traffic to islandflow-vps container names on the shared Docker network.
• Attempted docker compose down and forced container removal for the stale islandflow project, but those operations timed out when run as the normal deploy user.

Context

The repo has two Docker entry points with different purposes. The root docker-compose.yml is a local development infra stack that publishes NATS, ClickHouse, and Redis on host ports. The supported VPS deployment lives under deployment/docker/ and uses an islandflow-vps compose project, internal service-name routing, and Nginx Proxy Manager on the shared Docker network. Running both on the VPS creates duplicate infra and can make host-level debugging confusing.

Important Implementation Details

• The new warning is advisory only. It does not block Docker deploys, because the current live server still has the duplicate project and production deploys must keep working.
• The detection looks for containers whose compose project label is islandflow, which matches the repo-root stack on the VPS.
• The stale containers are still present as of this turn. Removal is blocked by hanging Docker operations and likely needs a maintenance window or host-level intervention.

[deploy] Warning: found an additional compose project named "islandflow" on the server.
[deploy] The live VPS should normally use only the deployment/docker stack (compose project "islandflow-vps").
[deploy] The repo-root docker-compose.yml is for local infra and can create duplicate exposed NATS, ClickHouse, and Redis services on the VPS.

Validation

• Passed: ./deploy --help
• Passed: bun run check:docker-workspace
• Passed: live VPS inspection confirming duplicate compose containers still exist
• Passed: public app health check after the cleanup attempt, https://flow.deltaisland.io still returned HTTP 200

ssh di 'docker ps --format "{{.Names}} {{.Label \"com.docker.compose.project\"}}" | grep "^islandflow-.* islandflow$" || true'
curl -I -fksS https://flow.deltaisland.io

Issues, Limitations, and Mitigations

• The stale VPS containers were not removed in this turn. Mitigation: tracked manual cleanup in islandflow-2db.
• Docker commands targeting those old containers hung and timed out. Mitigation: avoided risky broader actions that could impact the live islandflow-vps stack.
• The deploy warning is non-blocking. That is intentional so normal Docker deploys continue to work while the duplicate stack is still present.

Follow-up Work

• Open follow-up: islandflow-2db, manually remove the stale islandflow local-infra containers from the VPS during a maintenance window.