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/calcurse/hooks/pre-load

@@ -0,0 +1,5 @@
+#!/bin/sh
+# Sync with Google before the UI loads. Non-interactive calls (-Q, -d, -i, calcurse-caldav's own) run this hook
+# too, so act only for the UI: a bare "calcurse" with a terminal (the daemon is bare too, but has none).
+[ "$(ps -o args= -p "$PPID")" = calcurse ] && [ "$(ps -o tty= -p "$PPID" | tr -d ' ')" != '?' ] || exit 0
+calcurse-sync --now 2>&1 | systemd-cat -t calcurse-sync