Enable Evolution module and bind shortcut

Add core/evolution.nix with a toggleable option and import it in the
core
defaults. Enable the option on desktop, laptop, and default hosts.
Remove
the duplicated evolution‑data‑server enable flag from services.nix. Add
a
Hyprland keybinding (Super Shift E) to launch Evolution.

hosts/default/system-modules.nix

@@ -18,6 +18,11 @@ _: {
   */
   tailscale.enable = false; # Tailscale: secure network for remote access
 
+  /*
+  Calendar & Contacts
+  */
+  evolution.enable = true; # Evolution: calendar and contacts application
+
   /*
   Gaming
   */