calcurse: sync with Google Calendar via calcurse-caldav

Hourly timer started from xmonad, plus UI hooks that sync before load and after exit. calcurse-sync notifies once when the OAuth login expires and restarts the daemon after imports, since it never re-reads its files.

.config/xmonad/xmonad.hs

@@ -359,6 +359,7 @@ myStartupHook = do
   spawnOnce "arch-audit-gtk"
   spawnOnce "calcurse --daemon"
   spawnOnce "systemctl --user start calcurse-today.timer"
+  spawnOnce "systemctl --user start calcurse-sync.timer"
   spawnOnce "systemctl --user start dunst"
   spawnOnce "lxpolkit"
   spawnOnce "numlockx"