Add staging environment for testing worker scaling on Docker Swarm

[samuelvkwong]

Summary

Adds a staging deployment environment that enables testing worker scaling and Docker Swarm deployment features while maintaining development settings (DEBUG=True, debug toolbar, etc.).

Motivation

Currently, only production can use Docker Swarm for scaling workers. This PR enables developers to:

• Test worker scaling locally before deploying to production
• Test Docker Swarm deployment procedures
• Validate multi-worker concurrent processing behavior
• All while keeping dev-friendly settings (debug mode, detailed logging, etc.)

Changes

New Files

• docker-compose.staging.yml - Swarm deployment config with dev settings
• STAGING_DEPLOYMENT.md - Comprehensive deployment and usage guide

Modified Files

• example.env - Added staging port variables to avoid conflicts

Key Features

✅ Dev settings on Swarm: DEBUG=True, debug toolbar, console email
✅ Different ports: Runs on localhost:8001 (dev uses 8000)
✅ Pre-scaled workers: Starts with 3 mass_transfer_workers by default
✅ No config needed: Uses existing .env file
✅ All three can run together: Dev, staging, and production simultaneously

Port Allocation

No conflicts - all three environments can run at the same time:

Service	Dev	Staging	Production
Web UI	8000	8001	80, 443
PostgreSQL	5432	5433	(internal)
DICOM Receiver	11122	11123	11112
Orthanc1	7501	7503	(internal)
Orthanc2	7502	7504	(internal)

Usage

# Deploy staging (uses existing .env)
docker swarm init
docker stack deploy -c docker-compose.base.yml -c docker-compose.staging.yml adit-staging

# Access at http://localhost:8001

# Scale workers
docker service scale adit-staging_mass_transfer_worker=5

# Cleanup
docker stack rm adit-staging

Testing Checklist

• Verify staging deploys successfully
• Confirm accessible on http://localhost:8001
• Test worker scaling with docker service scale
• Verify all three environments can run simultaneously
• Confirm debug toolbar visible in staging

See STAGING_DEPLOYMENT.md for full documentation.

Summary by CodeRabbit

• New Features

  • Mass Transfer: bulk DICOM export with partitioned date ranges, JSON filter editor (CodeMirror), pseudonymization modes, optional DICOM→NIfTI conversion, job/task UI, volume listing, CSV export, background worker/queue with scaling, and preference persistence.

• Bug Fixes / Reliability

  • Improved task cancellation, DIMSE/connection cleanup, safer handling of empty/partial transfer responses, task timeout/cleanup hooks, and worker restart/resilience.

• Documentation

  • Staging deployment guide and full Mass Transfer specification added.

• Tests

  • Extensive tests for partitions, pseudonymization, processor behavior, forms, and cleanup.