Enable blue-green deployment strategy

Changes:
- Added [deploy] strategy = "bluegreen" to fly.toml
- Increased min_machines_running from 1 to 2
- Disabled auto_stop_machines to keep both environments ready
- Updated GitHub Actions workflow with --strategy bluegreen flag

How Blue-Green Works:
1. Deploy creates new "green" environment alongside current "blue"
2. Health checks verify green environment is healthy
3. Traffic switches instantly from blue to green
4. Old blue environment kept briefly for instant rollback
5. Zero downtime during deployments

Cost Impact:
- Runs minimum 2 machines instead of 1
- Ensures true zero-downtime deployments
- Instant rollback capability

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

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

.github/workflows/fly-deploy.yml

@@ -26,6 +26,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: superfly/flyctl-actions/setup-flyctl@master
-      - run: flyctl deploy --remote-only
+      - run: flyctl deploy --remote-only --strategy bluegreen
         env:
           FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}

fly.toml

@@ -6,14 +6,17 @@
 app = 'kjvstudy'
 primary_region = 'iad'
 
+[deploy]
+strategy = "bluegreen"
+
 [build]
 
 [http_service]
 internal_port = 8000
 force_https = true
-auto_stop_machines = 'suspend'
+auto_stop_machines = 'off'
 auto_start_machines = true
-min_machines_running = 1
+min_machines_running = 2
 processes = ['app']
 
 [http_service.concurrency]