fix: pass all .env vars to cameleer-saas via env_file

Instead of explicitly listing every env var the SaaS container needs,
use env_file to pass the entire .env. This ensures all installer-
configured values (passwords, hosts, ports, etc.) are available for
current and future use by the SaaS app and its provisioning config.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

installer/install.sh

@@ -840,6 +840,8 @@ EOF
     depends_on:
       logto:
         condition: service_healthy
+    env_file:
+      - .env
     environment:
       DOCKER_HOST: unix:///var/run/docker.sock
       SPRING_DATASOURCE_URL: jdbc:postgresql://postgres:5432/cameleer_saas