calcurse: one-click Google login renewal

On expiry calcurse-sync starts calcurse-relogin, a notification that opens the consent page when clicked and catches the OAuth code on 127.0.0.1:8749. dunst's left-click now runs a notification's action before closing it.

.config/systemd/user/calcurse-relogin.service

@@ -0,0 +1,7 @@
+[Unit]
+Description=Ask to renew the calcurse Google Calendar login
+
+[Service]
+# simple: the prompt waits for a click without a start timeout
+Type=simple
+ExecStart=%h/.local/bin/calcurse-relogin --prompt