fix(desktop): unfree CLI default, bar icon spacing, unified clock

Hardware findings on Latitude: nix-shell blocked unfree; whole-swap
bars collided icon+percentage; clock needed calcurse + one module.

- Export NIXPKGS_ALLOW_UNFREE=1 + ~/.config/nixpkgs/config.nix
- Mono Nerd face + trailing spaces on battery/volume icons (all bars)
- Single clock `HH:MM · Day DD Mon`; calcurse ships with waybar
- V3 queue entries for laptop re-check

Verification: V0 — nix flake check --no-build green; V2/V3 pending on
session (user-visible bar + CLI unfree).

themes/executive-slate/waybar.css

@@ -22,7 +22,9 @@
 @define-color bad       #D06B71;
 
 * {
-  font-family: "Inter", "Symbols Nerd Font", "JetBrainsMono Nerd Font", sans-serif;
+  /* Mono Nerd face first for status glyphs: proportional "Symbols Nerd
+     Font" has tight right bearings that make icon+percentage collide. */
+  font-family: "Symbols Nerd Font Mono", "Inter", "JetBrainsMono Nerd Font", sans-serif;
   font-size: 13px;
   font-weight: 500;
   border: none;
@@ -114,10 +116,11 @@ window#waybar {
   border-bottom: 2px solid @bad;
 }
 
-/* ── Clock — time (center) and date (left) share the #clock id ───── */
+/* ── Clock — unified time · date in one module ───────────────────── */
 #clock {
   color: @text;
   font-weight: 600;
+  font-family: "Inter", "Symbols Nerd Font Mono", sans-serif;
 }
 
 /* ── Status cluster: neutral by default, semantic on state ───────── */