fix(moonarch-git): add sweet-cursors dependency (pkgrel 15)

Moonarch configures the Sweet-cursors theme in six places — greeter
(moongreet.toml, niri-greeter.kdl) and desktop (niri config.kdl, GTK 3/4
settings.ini) — but never declared the package that ships the theme.
On a fresh install the cursor theme was absent system-wide, so Niri and
GTK fell back to the default cursor; it only worked where sweet-cursors
happened to be present (e.g. installed into a user home).

sweet-cursors-git provides 'sweet-cursors'; listing it ensures the theme
is installed system-wide for both the greeter user and the desktop user.

moonarch-git/PKGBUILD

@@ -5,7 +5,7 @@
 
 pkgname=moonarch-git
 pkgver=r127.806841d
-pkgrel=14
+pkgrel=15
 pkgdesc="Moonarch desktop environment defaults — Niri, Waybar, Catppuccin Mocha"
 arch=('any')
 url="https://gitea.moonarch.de/nevaforget/moonarch"
@@ -17,6 +17,7 @@ depends=(
     'moongreet'
     'moonlock'
     'moonset'
+    'sweet-cursors'
 
     # Compositor & session
     'niri'