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>

README.md

@@ -112,8 +112,8 @@ outbound mail will not reach the real internet without DNS, PTR, and port 25.
 > local image and pulls nothing:
 >
 > ```sh
-> docker build -f build/Dockerfile --build-arg VERSION=2.10.2 \
->   -t ghcr.io/mixeme/selfpost:2.10.2 .
+> docker build -f build/Dockerfile --build-arg VERSION=2.10.3 \
+>   -t ghcr.io/mixeme/selfpost:2.10.3 .
 > ```
 
 ```sh
@@ -122,7 +122,7 @@ docker run --rm -d --name selfpost-try \
   -e SELFPOST_HOSTNAME=mail.local.test \
   -e PANEL_COOKIE_SECURE=false \
   -v selfpost-try-data:/data \
-  ghcr.io/mixeme/selfpost:2.10.2
+  ghcr.io/mixeme/selfpost:2.10.3
 ```
 
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