release: 2.10.3: backup-reauth - the account password before a backup

Cut without asking, as the owner said on 2026-10-15. The full backup and a
domain's export ask for the signed-in user's account password under the
password change's limit; the import's file field is drawn as designed
(1888dce design, the code commit before this). go vet, go test (26
packages) and make e2e passed on the test server for that tree. No
migration, schema 12.

CHANGELOG [2.10.3]; pins in deploy/docker-compose.yml, README and the guide
(pin, build, the sample restore message); development's "from pin" and
row 35; roadmap row. No tag.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/roadmap.md

@@ -33,7 +33,7 @@ in `git log` and [CHANGELOG.md](../CHANGELOG.md).
 | test-email | Send a test message from the panel (was preflight) | agreed (2026-10-13) | — | — |
 | inbound-antispam-panel | Inbound antispam journal + allow/deny lists | shipped `2.1.0` | 12/12 | [plans/inbound-antispam-panel.md](plans/inbound-antispam-panel.md) |
 | origin-strict | Refuse a state-changing request that carries neither `Sec-Fetch-Site` nor `Origin` (was csrf-tokens) | agreed (2026-10-13) | — | — |
-| backup-reauth | Ask for the account password before a backup or a domain export is downloaded | done 2026-10-16, unreleased | — | — |
+| backup-reauth | Ask for the account password before a backup or a domain export is downloaded | shipped `2.10.3` | — | — |
 | review-2026-08-followups | Remaining findings of the 2026-08-19 code review | closed 2026-10-14 (rows placed in [audit-2026-10-12](audit-2026-10-12.md)) | — | — |
 | panel-notifications | E-mail notifications about important events | shipped `2.3.0` | 10/10 | [plans/panel-notifications.md](plans/panel-notifications.md) |
 | delivery-log-storage | Keep a message's `mail.log` lines with its send-log row | shipped `2.2.0` | 8/8 | [plans/delivery-log-storage.md](plans/delivery-log-storage.md) |