M5: upgrade + backup/restore stages green (custom-html); backup-bot-two oneshot

3-stage run green (install/upgrade/backup), clean teardown. backupbot deployed
via reconcile oneshot; PTY (script) for abra backup/restore; -m for secret generate
(no value leak). M5 CLAIMED.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

hosts/cc-ci/configuration.nix

@@ -13,6 +13,7 @@
     ../../modules/drone.nix
     ../../modules/drone-runner.nix
     ../../modules/bridge.nix
+    ../../modules/backupbot.nix
     ../../modules/harness.nix
   ];