feat(genre): play, shuffle and queue buttons on the genre view (#926)

* feat(genre): add paginated songs-by-genre API

Wraps the Subsonic getSongsByGenre endpoint plus a fetchAllSongsByGenre
helper that paginates until exhausted, capped to keep the queue and the
burst of requests bounded for very large genres.

* refactor(playback): extract shared bulk play/shuffle/enqueue helper

A single fetchTracks-driven core (loading flag, empty guard, canonical
shuffleArray) so async detail-page play buttons stop growing divergent
copies. Artist detail now reuses it, dropping its weaker sort-random
shuffle.

* feat(genre): play, shuffle and queue buttons on the genre view

Header buttons load the genre's songs and start ordered or shuffled
playback, or append them to the queue. The slice is bounded to stay
within the queue resolver's cache budget so every row resolves instead
of rendering as a placeholder. Strings added across all nine locales.

* docs(changelog): genre play/shuffle buttons (#926)

CHANGELOG.md

@@ -179,6 +179,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 
+### Genre detail — play or shuffle a whole genre
+
+**By [@Psychotoxical](https://github.com/Psychotoxical), PR [#926](https://github.com/Psychotoxical/psysonic/pull/926)**
+
+* Play, Shuffle and Add-to-queue buttons on a genre page start the whole genre in one click — in order or randomized — instead of adding each album by hand. Suggested by Apollosport.
+
+
+
 ## Changed
 
 ### CI — hot-path coverage gates block merges