release: 2.10.1: long, non-repeating queue ids

Cut without asking, as the owner said on 2026-10-15, after his choice of
2026-10-16 ("1"): Postfix makes long queue ids (enable_long_queue_ids=yes),
so a later message can no longer meet an earlier one's rows. go vet, go test
(26 packages) and make e2e passed on the test server for that tree, long
ids on both an outbound and an inbound row. No migration, schema 12.

CHANGELOG [2.10.1]; pins in deploy/docker-compose.yml, README and the guide
(pin, build, the sample restore message); development's "from pin" and
row 33. 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=2.10.0 \
->   -t ghcr.io/mixeme/selfpost:2.10.0 .
+> docker build -f build/Dockerfile --build-arg VERSION=2.10.1 \
+>   -t ghcr.io/mixeme/selfpost:2.10.1 .
 > ```
 
 ```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:2.10.0
+  ghcr.io/mixeme/selfpost:2.10.1
 ```
 
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