Revert to min_machines_running = 1

Keep blue-green deployment strategy but with single minimum machine to reduce costs. During deployment, Fly.io will:
- Start new machine (green)
- Run health checks
- Switch traffic
- Stop old machine (blue)

Note: This may have brief startup time during deployment, but significantly reduces operating costs.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

fly.toml

@@ -14,9 +14,9 @@ strategy = "bluegreen"
 [http_service]
 internal_port = 8000
 force_https = true
-auto_stop_machines = 'off'
+auto_stop_machines = 'suspend'
 auto_start_machines = true
-min_machines_running = 2
+min_machines_running = 1
 processes = ['app']
 
 [http_service.concurrency]