Point the rc ISO's [omarchy] repo at the rc channel

The Arch base repos already come from rc-mirror.omarchy.org, but
[omarchy] still pointed at edge — a leftover from when release
candidates published there. RCs now publish to the dedicated rc
channel on pkgs.omarchy.org, so an rc ISO built against edge would
install the previous release instead of the candidate.

configs/pacman-online-rc.conf

@@ -27,7 +27,7 @@ Include = /etc/pacman.d/mirrorlist
 
 [omarchy]
 SigLevel = Optional TrustAll
-Server = https://pkgs.omarchy.org/edge/$arch
+Server = https://pkgs.omarchy.org/rc/$arch
 
 [arch-mact2]
 Server = https://github.com/NoaHimesaka1873/arch-mact2-mirror/releases/download/release