fix: the first write of a newer wall model is not an outdated client (#319)

A stale client can only echo the stored model_version, never raise it. The
'unchanged wall catalogue' refusal now applies only when the submitted model
is not above the stored one; the first v9 write over a v8 document with an
orphan open_span/open_to legitimately drops the legacy projection without
touching the catalogue and passes. The regression pair fixture is produced
by the real writers (stored: v1.68.0-beta.2, sent: current migration) and is
pinned on the frontend byte-for-byte so it cannot drift.

Issue: #319
User-Visible: yes

docs/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## Unreleased
 
+- Updating to the new wall model no longer freezes editing: the server now
+  recognises the first write of a newer card over an older document (for
+  example one that still carried an orphan legacy border) instead of demanding
+  a card update that was already installed
+  ([#319](https://github.com/Matysh/houseplan-card/issues/319)).
+
 ## v1.68.0-beta.3 — 2026-08-26
 
 - Walls now use one model at every thickness. The separate **Boundary** tool

docs/CHANGELOG.ru.md

@@ -8,6 +8,12 @@
 
 ## Не выпущено
 
+- Обновление на новую модель стен больше не замораживает редактирование:
+  сервер распознаёт первую запись более новой карточки поверх старого
+  документа (например, с осиротевшей легаси-границей) вместо требования
+  обновить уже обновлённую карточку
+  ([#319](https://github.com/Matysh/houseplan-card/issues/319)).
+
 ## v1.68.0-beta.3 — 2026-08-26
 
 - Теперь у стен одна модель при любой толщине. Отдельные инструмент