fix(desktop): hardware findings — charge limit, polkit ws, bar deps

Latitude 5310 QA:
- Clock tooltip: drop empty {calendar} popup; plain date+zone
- Charge limit: restart oneshot via polkit + dual write/delay for
  Dell unplug race; toast verifies sysfs; looser menu match
- pwvucontrol ships with waybar (right-click volume)
- Print/region→clipboard toasts success
- Polkit (and pinentry) open on current workspace + stayfocused

V0: flake check --no-build green. V3: retest A3/A4/B1/tooltip/polkit.

modules/home/keybinds.nix

@@ -72,7 +72,7 @@
     # Bare Print → region to clipboard; the two → file binds save a
     # timestamped PNG under ~/Pictures/Screenshots and toast the path, the
     # same plumbing the Capture menu's "→ file" rows use.
-    { mods = "";            key = "Print";  action = "exec, grim -g \"$(slurp)\" - | wl-copy"; desc = "Screenshot region → clipboard"; }
+    { mods = "";            key = "Print";  action = "exec, grim -g \"$(slurp)\" - | wl-copy && notify-send Screenshot \"Region copied to clipboard.\""; desc = "Screenshot region → clipboard"; }
     { mods = "SHIFT";       key = "Print";  action = "exec, f=$HOME/Pictures/Screenshots/$(date +%Y%m%d-%H%M%S).png; mkdir -p $HOME/Pictures/Screenshots && grim -g \"$(slurp)\" \"$f\" && notify-send \"Screenshot saved\" \"$f\""; desc = "Screenshot region → file"; }
     { mods = "CTRL";        key = "Print";  action = "exec, f=$HOME/Pictures/Screenshots/$(date +%Y%m%d-%H%M%S).png; mkdir -p $HOME/Pictures/Screenshots && grim \"$f\" && notify-send \"Screenshot saved\" \"$f\""; desc = "Screenshot screen → file"; }
     { mods = "$mod SHIFT";  key = "Print";  action = "exec, f=$HOME/Pictures/Screenshots/$(date +%Y%m%d-%H%M%S).png; mkdir -p $HOME/Pictures/Screenshots && grim -g \"$(slurp)\" - | satty --filename - --fullscreen --output-filename \"$f\""; desc = "Annotate region"; }