fix(traefik): Update HostRegexp syntax for Traefik v3

Traefik v3 changed HostRegexp syntax from named capture groups to
standard regex. Added low priority to avoid matching specific routes.

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

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

smoothschedule/compose/production/traefik/traefik.yml

@@ -100,7 +100,8 @@ http:
     # Uses DNS challenge for wildcard certificate (*.smoothschedule.com)
     # Routes to nginx which serves the frontend SPA and proxies /api/ to Django
     subdomain-router:
-      rule: 'HostRegexp(`{subdomain:[a-z0-9-]+}.smoothschedule.com`)'
+      rule: 'HostRegexp(`^[a-z0-9-]+\\.smoothschedule\\.com$`)'
+      priority: 1
       entryPoints:
         - web-secure
       middlewares: