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/config/settingsCredits.ts

@@ -356,7 +356,7 @@ const CONTRIBUTOR_ENTRIES = [
       'Performance Probe: Monitor/Toggles redesign, live CPU/RSS/thread metrics, overlay pins and sparklines, macOS snapshots (PR #890)',
       'Performance Probe: opt-in thread-group CPU poll toggle and includeThreadGroups IPC fix (PR #891)',
       'Queue: switchable display mode — Queue (upcoming only) vs Playlist (full list), with header toggle and settings entry (PR #922)',
-      'Community Theme Store: semantic-token refactor, dedicated Themes tab with day/night scheduler, install/update/uninstall, local .zip import, and free-form community themes (safety floor + state-reactive styling); 80+ palettes moved to an on-demand CDN repo (PR #1009, #1011, #1012, #1013, #1014, #1015)',
+      'Community Theme Store: semantic-token refactor, dedicated Themes tab with day/night scheduler, install/update/uninstall, local .zip import, and free-form community themes (safety floor + state-reactive styling); 80+ palettes moved to an on-demand CDN repo (PR #1009, #1011, #1012, #1013, #1014, #1015, #1016)',
     ],
   },
   {