Share hypr_refresh; capture the work laptop's own units

Both laptops run hypr_refresh and their unit files had diverged. The work
laptop's is the refined one — Type=oneshot, which is correct for a script
that exits, a 15s interval with AccuracySec, and a comment explaining the
wallpaper-daemon guard. system76 had Type=simple with Restart=on-failure,
which respawns a oneshot script continuously. Shared version wins.

Three more units existed only on the work laptop and were untracked:
backlight-probe, kanshi and mopidy.

common/systemd/hypr_refresh.service

@@ -0,0 +1,7 @@
+[Unit]
+Description=Refresh Hyprland wallpaper and colorscheme
+After=graphical-session.target
+
+[Service]
+Type=oneshot
+ExecStart=%h/.dotfiles/common/bin/hypr_refresh

common/systemd/hypr_refresh.timer

@@ -0,0 +1,12 @@
+[Unit]
+Description=Refresh Hyprland wallpaper/colorscheme every 15 seconds
+
+[Timer]
+# First run shortly after login (guard in the script no-ops if the wallpaper
+# daemon isn't up yet), then every 15s thereafter.
+OnBootSec=30sec
+OnUnitActiveSec=15sec
+AccuracySec=1s
+
+[Install]
+WantedBy=timers.target