feat(themes): fresher store refresh + external-services notice (#1016)

* feat(themes): fresher store refresh + external-services notice

Manual refresh now fetches the registry from GitHub raw first (~5 min
cache) and falls back to the jsDelivr CDN, so a freshly merged theme shows
up without waiting on — or purging — the shared CDN @main edge (up to
12 h). Normal loads still use the CDN.

Adds a notice on the Theme Store that the catalogue and previews load from
external services (jsDelivr / GitHub), in line with the app's network
transparency. i18n ×9.

* docs(themes): note the store-refresh PR in the Theme Store entry

Now that #1015 is merged, fold PR #1016 into the still-unreleased Theme
Store changelog and credits entry.

src/locales/ru/settings.ts

@@ -405,6 +405,7 @@ export const settings = {
   themeStoreTitle: 'Магазин тем',
   themeStoreSubmitText: 'Создали свою тему? Поделитесь с сообществом — подробности в репозитории тем.',
   themeStoreSubmitLink: 'Открыть репозиторий тем',
+  themeStoreNetworkNotice: 'Магазин тем загружает каталог и превью с внешних сервисов (CDN jsDelivr и GitHub). Личные данные не отправляются.',
   themeStoreSearchPlaceholder: 'Поиск тем…',
   themeStoreFilterMode: 'Фильтр по режиму',
   themeStoreModeAll: 'Все',