fix: store Authelia credentials in persistent location

- setup-homelab.sh: Store temp files in /opt/stacks/.setup-temp instead of /tmp
- deploy-homelab.sh: Read credentials from new persistent location
- reset-test-environment.sh: Clean up new temp directory

This fixes the issue where credentials were inaccessible when deploy script
runs via 'su -' (login shell) from setup script, as /tmp files created by
root are not accessible across the su boundary.

scripts/reset-test-environment.sh

@@ -122,6 +122,8 @@ echo ""
 log_info "Step 4/6: Cleaning temporary files..."
 
 rm -f /tmp/authelia_admin_credentials.tmp
+rm -f /tmp/authelia_password_hash.tmp
+rm -rf /opt/stacks/.setup-temp
 rm -f /tmp/nvidia*.log
 log_success "Temporary files cleaned"
 echo ""