feat: add deployment automation for production

[cfsmp3]

Summary

• Remove obsolete VITE_* build-args from docker.yml (frontend now uses relative URLs after feat: use relative URLs for frontend API calls #439)
• Add deploy.yml workflow for manual production deployments via SSH
• Add deployment/ directory with production docker-compose.yml and deploy.sh script
• Add comprehensive README with VPS setup instructions

How It Works

1. Push to main triggers existing docker.yml → builds images, pushes to GHCR
2. Manually trigger "Deploy to Production" workflow with image tag
3. Workflow SSHs to VPS and runs /opt/ccsync/scripts/deploy.sh <tag>
4. Script pulls images, starts containers, verifies health, rolls back on failure

VPS Requirements

Before using this, the VPS needs:

• deploy user with docker access
• /opt/ccsync/ directory structure
• SSH key for GitHub Actions
• GitHub environment "production" with SSH credentials

See deployment/README.md for full setup instructions.

Test plan

• Review workflow files for correctness
• Set up VPS infrastructure (separate task)
• Configure GitHub environment with SSH credentials
• Test manual deployment trigger

🤖 Generated with Claude Code

[github-actions]

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