feat(moonarch-git): stage + deploy mpv configs via post_install

Stages defaults/etc/mpv/ to /usr/share/moonarch/mpv/ and copies
mpv.conf + modernz.conf into /etc/mpv/ on install. modernz.conf
deliberately overwrites the AUR default from mpv-modernz-git.
pkgrel bumped to 11.

moonarch-git/moonarch.install

@@ -29,6 +29,12 @@ post_install() {
     cp /usr/share/moonarch/swaync/config.json /etc/xdg/swaync/config.json
     cp /usr/share/moonarch/swaync/style.css /etc/xdg/swaync/style.css
 
+    # Deploy mpv configs (modernz.conf owned by mpv-modernz-git, overwrite deliberately)
+    install -Dm644 /usr/share/moonarch/mpv/mpv.conf /etc/mpv/mpv.conf
+    if [ -d /etc/mpv/script-opts ]; then
+        cp /usr/share/moonarch/mpv/modernz.conf /etc/mpv/script-opts/modernz.conf
+    fi
+
     # Deploy Walker config override to skel and existing user homes.
     # Only copies if user has no config yet — never overwrites manual edits.
     install -Dm644 /usr/share/moonarch/walker-config.toml \