Retire Docker-based tools to unused/

Docker is not installed on pet630, so neither of these can run there:

- docker-idrac.sh is the container-based alternative to the ipmi-fancontrol
  scripts, which remain in service.
- webnut-docker/ is the web UI for the NUT daemon. NUT itself is still
  running on the host; only this front end is retired.

The gitignored .env moves with the compose file and is still excluded at the
new path.

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

unused/webnut-docker/.env.example

@@ -0,0 +1,7 @@
+# Copy to .env next to docker-compose.yml; Compose loads it automatically.
+#   cp .env.example .env && chmod 0600 .env
+
+UPS_HOST=10.20.28.200
+UPS_PORT=3493
+UPS_USER=adminuser
+UPS_PASSWORD=changeme