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>

BACKLOG.md

@@ -46,8 +46,10 @@ Two single-writer sections (§6.1): Builder edits only `## Build backlog`; Adver
       → 2 passed (http 200 + playwright); teardown leaves services/volumes/secrets/containers/env = 0.
 
 ### M5 — Upgrade + backup/restore stages
-- [ ] Add upgrade + backup/restore stages for recipe #1
-- [ ] Gate: M5 — upgrade preserves data; backup→mutate→restore returns original
+- [x] Add upgrade + backup/restore stages for recipe #1 (custom-html). backup-bot-two deployed as a
+      reconcile oneshot (modules/backupbot.nix). Data marker served via nginx for assertions.
+- [x] Gate: M5 — upgrade preserves data; backup→mutate→restore returns original → CLAIMED 2026-05-27.
+      Full 3-stage run green: install(2)+upgrade(1)+backup(1) passed; teardown leaves 0 orphans, infra intact.
 
 ### M6 — Recipe-local tests + second recipe
 - [ ] Discover/run recipe-repo tests/; enroll DB-backed recipe #2