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>

hosts/live-iso.nix

@@ -1,19 +1,8 @@
-{ config, pkgs, inputs, lib, homeActivationPackage, ... }:
+{ config, pkgs, inputs, lib, ... }:
 
 {
-  # Pre-activate standalone home-manager for the live environment
-  system.activationScripts.home-manager-activate = {
-    text = ''
-      USER_HOME="/home/nixos"
-      if [ ! -d "$USER_HOME" ]; then
-        mkdir -p "$USER_HOME"
-        chown nixos:users "$USER_HOME"
-      fi
-      # Run activation as the nixos user
-      ${pkgs.sudo}/bin/sudo -u nixos ${homeActivationPackage}/activate
-    '';
-    deps = [ "users" ];
-  };
+  # Home Manager activation for the nixos live user is provided by the
+  # home-manager.nixosModules.home-manager module wired up in flake.nix.
 
   environment.systemPackages = with pkgs; [
     git
@@ -35,9 +24,11 @@
   # Ensure the live environment user has the necessary groups for graphical acceleration and audio
   users.users.nixos.extraGroups = [ "wheel" "video" "render" "audio" "networkmanager" ];
 
-  # Graphics support for live environment
-  boot.initrd.kernelModules = [ "amdgpu" "radeon" "nouveau" "i915" ];
-  services.xserver.videoDrivers = [ "amdgpu" "radeon" "nouveau" "modesetting" "fbdev" ];
+  # Graphics support for live environment.
+  # `virtio` is a no-op on real hardware (no virtio-gpu PCI device) but lets
+  # the ISO render correctly when booted in QEMU via nomarchy-test-live-iso.
+  boot.initrd.kernelModules = [ "amdgpu" "radeon" "nouveau" "i915" "virtio_gpu" ];
+  services.xserver.videoDrivers = [ "amdgpu" "radeon" "nouveau" "modesetting" "fbdev" "virtio" ];
 
   environment.etc."install.sh" = {
     source = ../installer/install.sh;