Add admin users, BYOC teams, hosts schema, and Redis for host registration

Introduce three migrations: admin permissions (is_admin + permissions table),
BYOC team tracking, and multi-host support (hosts, host_tokens, host_tags).
Add Redis to dev infra and wire up client in control plane for ephemeral
host registration tokens. Add go-redis dependency.

deploy/docker-compose.dev.yml

@@ -10,6 +10,11 @@ services:
     volumes:
       - pgdata:/var/lib/postgresql/data
 
+  redis:
+    image: redis:7-alpine
+    ports:
+      - "6379:6379"
+
   prometheus:
     image: prom/prometheus:latest
     ports: