feat(themes): sidebar notice when an installed theme has an update (#1041)

* feat(themes): sidebar notice when an installed theme has an update

Adds a dismissible sidebar pill (sibling of the What's New banner) shown
while an installed community theme has a newer version in the store. Clicking
opens Settings -> Themes; dismiss hides it until a new update changes the set.

The theme registry is now refreshed from source once per app launch instead
of only when the Theme Store tab is opened, so newly published themes and
updates surface without a manual refresh -- and feed this notice.

* docs: add CHANGELOG entry for PR #1041

* feat(themes): in-place update control on installed theme cards

Themes with a newer version in the store now show a centered update icon on
their card in Settings -> Themes; clicking it fetches and reinstalls in place.
Extracts the shared installThemeFromRegistry helper (fetch -> validate ->
install) used by both the store list and the card control, and surfaces the
full registry entry from useThemeUpdates so the card can update directly.

CHANGELOG.md

@@ -56,7 +56,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Themes — community Theme Store
 
-**By [@Psychotoxical](https://github.com/Psychotoxical), PR [#1009](https://github.com/Psychotoxical/psysonic/pull/1009), [#1011](https://github.com/Psychotoxical/psysonic/pull/1011), [#1012](https://github.com/Psychotoxical/psysonic/pull/1012), [#1013](https://github.com/Psychotoxical/psysonic/pull/1013), [#1014](https://github.com/Psychotoxical/psysonic/pull/1014), [#1015](https://github.com/Psychotoxical/psysonic/pull/1015), [#1016](https://github.com/Psychotoxical/psysonic/pull/1016), [#1018](https://github.com/Psychotoxical/psysonic/pull/1018), [#1020](https://github.com/Psychotoxical/psysonic/pull/1020), [#1036](https://github.com/Psychotoxical/psysonic/pull/1036), [#1038](https://github.com/Psychotoxical/psysonic/pull/1038)**
+**By [@Psychotoxical](https://github.com/Psychotoxical), PR [#1009](https://github.com/Psychotoxical/psysonic/pull/1009), [#1011](https://github.com/Psychotoxical/psysonic/pull/1011), [#1012](https://github.com/Psychotoxical/psysonic/pull/1012), [#1013](https://github.com/Psychotoxical/psysonic/pull/1013), [#1014](https://github.com/Psychotoxical/psysonic/pull/1014), [#1015](https://github.com/Psychotoxical/psysonic/pull/1015), [#1016](https://github.com/Psychotoxical/psysonic/pull/1016), [#1018](https://github.com/Psychotoxical/psysonic/pull/1018), [#1020](https://github.com/Psychotoxical/psysonic/pull/1020), [#1036](https://github.com/Psychotoxical/psysonic/pull/1036), [#1038](https://github.com/Psychotoxical/psysonic/pull/1038), [#1041](https://github.com/Psychotoxical/psysonic/pull/1041)**
 
 * New **Settings → Themes** tab: pick a theme, set the day/night scheduler, and browse a built-in **Theme Store** to install, update and uninstall community themes — with search, a dark/light filter, and full-size thumbnail previews.
 * The app now bundles six core themes (Catppuccin Mocha & Latte, Kanagawa Wave, Stark HUD, and the colour-blind-safe Vision Dark / Vision Navy); every other palette installs on demand from the [psysonic-themes](https://github.com/Psysonic/psysonic-themes) repo. Installed themes are saved locally and apply instantly at startup, even offline.
@@ -65,6 +65,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * The store paginates large catalogues, and refreshing the list no longer jumps back to the top.
 * Each store theme shows its **total downloads** and a **last-changed** date, and can be sorted by most popular, newest or name; the catalogue now has numbered page navigation. These stats refresh once a day.
 * The **Now Playing** page now follows the active theme end to end — light themes render it legibly instead of washed-out, with no per-theme tweaks needed.
+* The sidebar now shows a small notice when one of your installed themes has an update available — click it to jump straight to the Theme Store, or dismiss it until the next update. Themes with an update also show an update control right on their card under **Settings → Themes** to update them in place with one click, and the store refreshes once on startup so new themes and updates show up without hitting refresh.
 * Upgrading from an older build: an active or scheduled theme that has moved to the store and isn't installed falls back to Mocha (dark) / Latte (light).