feat: make VM and live ISO match an installed Nomarchy

- Migrate VM and graphical ISO to home-manager.nixosModules.home-manager;
  drop the standalone-HM sudo-based activation script (ran HM against
  /root because HOME wasn't reset) in flake.nix, core/system/vm-guest.nix,
  hosts/live-iso.nix.
- Run swaybg as nomarchy-wallpaper.service instead of a silent Hyprland
  exec-once so failures surface in systemctl.
- Skip the battery monitor unit on hosts without /sys/class/power_supply/BAT*
  (VMs, desktops).
- Don't wrap walker --dmenu in uwsm-app; redirect setsid background std-fds
  in nomarchy-launch-walker so $(menu ...) in nomarchy-menu doesn't hang.
- Restart waybar/walker via systemctl --user rather than pkill + uwsm-app
  to stop the post-theme-switch color race.
- Wire nomarchy-restart-walker/-waybar into nomarchy-theme-set so themes
  that only change the imported CSS reload correctly.
- Waybar: pin #custom-nomarchy to the Nomarchy font and use the U+F000
  codepoint so the logo shows across all themes.
- Auto-install the correct icon-theme package per palette via a new
  nomarchyLib.iconThemePackage helper in lib/default.nix; Everforest now
  actually renders for summer-night.
- Pre-cache every theme's HM generation: new packages.allThemeVariants
  flake output and nomarchy-themes-prebuild script so theme switches are
  cache-only (no Stylix rebuild, no downloads).
- Add nomarchy-test-live-iso to boot the graphical ISO in QEMU the same
  way nomarchy-test-vm does, with virtio-gpu support added to live-iso.nix.
- Installer-generated home.nix/system.nix now ship a curated, commented
  app menu (btop/fastfetch/chromium on by default) plus optional system
  services (Docker, libvirtd, Tailscale, Syncthing, Flatpak, Steam).
- nomarchy-test-vm now wipes the stale nomarchy.qcow2 before launch.
- Remove obsolete GEMINI.md and PLAN.md.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

features/desktop/hyprland/default.nix

@@ -50,4 +50,24 @@ in
   xdg.configFile."hypr/bindings.conf".source = lib.mkDefault ./config/bindings.conf;
   xdg.configFile."hypr/looknfeel.conf".source = lib.mkDefault ./config/looknfeel.conf;
   xdg.configFile."hypr/autostart.conf".source = lib.mkDefault ./config/autostart.conf;
+
+  # Run swaybg as a proper systemd user service rather than a Hyprland exec-once.
+  # exec-once fails silently (black screen with no visible error) when timing
+  # against uwsm's graphical-session target is off; a service surfaces failures
+  # via `systemctl --user status nomarchy-wallpaper` and auto-restarts.
+  systemd.user.services.nomarchy-wallpaper = {
+    Unit = {
+      Description = "Nomarchy desktop wallpaper (swaybg)";
+      PartOf = [ "graphical-session.target" ];
+      After = [ "graphical-session.target" ];
+    };
+    Service = {
+      ExecStart = "${pkgs.swaybg}/bin/swaybg -i %h/.config/nomarchy/current/background -m fill";
+      Restart = "on-failure";
+      RestartSec = "2";
+    };
+    Install = {
+      WantedBy = [ "graphical-session.target" ];
+    };
+  };
 }