i3: improve automatic/timeout/suspend locking

.config/systemd/user/sleep-i3lock@.service

@@ -1,10 +0,0 @@
-[Unit]
-Description=Lock X session using i3lock
-
-[Service]
-User=%i
-Environment=DISPLAY=:0
-ExecStart=sh -c '~/.config/i3/lock.sh'
-
-[Install]
-WantedBy=sleep.target

.config/systemd/user/sleep-lock-lightdm.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Lock X LightDM session before sleeping
+Before=sleep.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/dm-tool switch-to-greeter
+# Ensure enough time for the session to lock before sleeping
+ExecStartPost=/usr/bin/sleep 1
+
+[Install]
+WantedBy=sleep.target

.config/systemd/user/sleep.target.wants/sleep-lock-lightdm.service

@@ -0,0 +1 @@
+../sleep-lock-lightdm.service