fix: wait for minio-init before starting web

web only depended on minio being healthy, not on minio-init having
created the upload bucket — a race on cold deploys, and likely why
the deploy tool flagged minio-init's exit(0) as an anomaly (it wasn't
wired into the dependency graph the way migrate is).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

compose.prod.yml

@@ -122,6 +122,8 @@ services:
         condition: service_started
       minio:
         condition: service_healthy
+      minio-init:
+        condition: service_completed_successfully
 
   # Fires the weekly digest email send by POSTing to `web`'s internal cron
   # route on a schedule (see cron/crontab). Tiny alpine+curl+crond