disable auto-stop to prevent cold start latency

BEAM cold starts on shared-cpu-1x take ~15s, making the site
unusable after idle periods. Keep the single machine running.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

fly.toml

@@ -20,7 +20,7 @@ primary_region = 'lhr'
 [http_service]
   internal_port = 4000
   force_https = true
-  auto_stop_machines = 'stop'
+  auto_stop_machines = 'off'
   auto_start_machines = true
   min_machines_running = 1