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/de/settings.ts

@@ -327,6 +327,7 @@ export const settings = {
   themeStoreTitle: 'Theme-Store',
   themeStoreSubmitText: 'Eigenes Theme gebaut? Teil es mit der Community — mehr Infos im Themes-Repository.',
   themeStoreSubmitLink: 'Themes-Repository öffnen',
+  themeStoreNetworkNotice: 'Der Theme-Store lädt Katalog und Vorschauen von externen Diensten (jsDelivr-CDN und GitHub). Es werden keine persönlichen Daten gesendet.',
   themeStoreSearchPlaceholder: 'Themes suchen…',
   themeStoreFilterMode: 'Nach Modus filtern',
   themeStoreModeAll: 'Alle',