fix(installer): unblock disko, bootloader, HM activation, hyprland res

- Pass --yes-wipe-all-disks to disko so the silent gum-spin path no
  longer hangs forever waiting on a hidden "yes" confirmation prompt
  (added in disko 1.13's destroy,format,mount mode).
- Stop threading an externally-built pkgs into the user flake's
  nixosSystem; configure nixpkgs through the module system instead so
  core/system/default.nix's nixpkgs.config.allowUnfree stops conflicting
  with the assertion "system configures nixpkgs with an externally
  created instance".
- Enable boot.loader.systemd-boot in the generated system.nix so the
  installed system has an actual bootloader (disko already lays out a
  1 GiB ESP at /boot).
- Bump nix.settings.download-buffer-size to 512 MiB to silence the
  "download buffer is full" warning on large NAR fetches.
- Activate home-manager via `runuser -l` instead of `runuser -u … --
  env HOME=…`. The latter only switches uid and leaves \$USER=root, so
  HM's activation script saw root, warned, and wrote dotfiles into
  /root/ — meaning the user's first login had no Hyprland config.
- Revert default Hyprland monitor line back to highres (live ISO and
  user default) — preferred falls back to EDID's 1024x768 in QEMU and
  on several laptop panels, which is the bug highres was put there to
  defeat.

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

core/system/nix.nix

@@ -11,6 +11,14 @@
       
       # Optimize storage by hard-linking identical files
       auto-optimise-store = lib.mkDefault true;
+
+      # Bump the substituter download buffer from the 64 MiB default to
+      # 512 MiB. Large NARs (kernels, electron apps, the full NixOS
+      # closure on first install) overrun 64 MiB and Nix prints
+      # "download buffer is full" until the consumer catches up — the
+      # warning is harmless but slows substitution and looks like an
+      # error. 512 MiB comfortably covers everything in our closure.
+      download-buffer-size = 524288000;
     };
 
     # Populates NIX_PATH with the nixpkgs input from the flake.

features/desktop/hyprland/config/monitors.conf

@@ -13,7 +13,7 @@
 # Straight 1x setup for low-resolution displays like 1080p or 1440p
 # Or for ultrawide monitors like 34" 3440x1440 or 49" 5120x1440
  env = GDK_SCALE,1
- monitor=,preferred,auto,1
+ monitor=,highres,auto,1
 
 # Portrait/rotated secondary monitor (transform: 1 = 90°, 3 = 270°)
 # monitor = DP-2, preferred, auto, 1, transform, 1

flake.nix

@@ -168,10 +168,10 @@
               # Live-ISO-only welcome. Pops a notification a few seconds
               # after the graphical session is up and opens a terminal
               # parked at the installer command, so the user never has to
-              # hunt for it. Force preferred monitor detection as some
+              # hunt for it. Force highres monitor detection as some
               # hardware defaults to 1024x768.
               wayland.windowManager.hyprland.extraConfig = nixpkgs.lib.mkAfter ''
-                monitor = , preferred, auto, 1
+                monitor = , highres, auto, 1
                 exec-once = sh -c 'sleep 3; notify-send -u critical -t 0 "Welcome to Nomarchy" "Run \`sudo /etc/install.sh\` in the open terminal — or \`--dry-run\` to preview."'
 
                 exec-once = sh -c 'sleep 4; alacritty --title "Nomarchy Installer" -e bash -lc "echo; echo \"Welcome to the Nomarchy live ISO.\"; echo; echo \"  sudo /etc/install.sh           # install\"; echo \"  sudo /etc/install.sh --dry-run # preview only\"; echo \"  sudo /etc/install.sh --resume  # resume after an interrupt\"; echo; exec bash"'

installer/install.sh

@@ -1110,6 +1110,7 @@ run_disko_with_retry() {
         if [[ "$NOMARCHY_VERBOSE_DISKO" == "1" ]]; then
             set +e
             disko --mode destroy,format,mount \
+                  --yes-wipe-all-disks \
                   --argstr mainDrive "$main_drive" \
                   --arg    extraDrives "$extras_nix" \
                   "$disko_file" 2>&1 | tee "$log"
@@ -1125,6 +1126,7 @@ run_disko_with_retry() {
             nrun gum spin --spinner dot --title "Partitioning disk(s) with disko..." -- \
                 bash -c '
                     disko --mode destroy,format,mount \
+                          --yes-wipe-all-disks \
                           --argstr mainDrive "$1" \
                           --arg    extraDrives "$2" \
                           "$3" > "$4" 2>&1
@@ -1256,16 +1258,18 @@ execute_installation() {
 
     # 9.8 Activate Home Manager for $USERNAME inside the new system so the
     # user's first login already has Nomarchy's dotfiles. `home-manager
-    # switch` must run as the target user with a real $HOME, so we use
+    # switch` must run as the target user with a real \$HOME *and* a
-    # `runuser` (sudo -u keeps the caller's HOME → files land in /root).
+    # \$USER env var pointing at them — home-manager's activation script
+    # bails with "running as root" if \$USER is still root, even when the
+    # uid has been switched. `runuser -l` runs a login shell, which sets
+    # HOME, USER, LOGNAME, and SHELL from the user database; plain
+    # `runuser -u … -- env HOME=…` switches uid only and leaves \$USER
+    # as root, which is what landed the dotfiles in /root previously.
     info "Activating Home Manager for $USERNAME..."
     if nixos-enter --root /mnt -- bash -c "
         set -e
         install -d -o '$USERNAME' -g users -m 0755 '/home/$USERNAME'
-        runuser -u '$USERNAME' -- env HOME='/home/$USERNAME' \
+        runuser -l '$USERNAME' -c \"nix --extra-experimental-features 'nix-command flakes' run 'home-manager/release-25.11' -- switch --flake '/etc/nixos#$USERNAME' --impure\"
-            nix --extra-experimental-features 'nix-command flakes' \
-            run 'home-manager/release-25.11' -- switch \
-            --flake '/etc/nixos#$USERNAME' --impure
     "; then
         success "Home Manager activated"
     else
@@ -1424,9 +1428,12 @@ generate_flake_config() {
     in
     {
       nixosConfigurations.$HOSTNAME = nixpkgs.lib.nixosSystem {
-        inherit pkgs;
         specialArgs = { inputs = nomarchy.inputs; };
         modules = [
+          {
+            nixpkgs.hostPlatform = system;
+            nixpkgs.overlays = [ nomarchy.overlays.default ];
+          }
           ./hardware-configuration.nix
           ./hardware-selection.nix
           nomarchy.nixosModules.system
@@ -1479,6 +1486,11 @@ EOF
   networking.hostName = "$HOSTNAME";
   time.timeZone = "$TIMEZONE";
 
+  # UEFI bootloader. Disko lays out a 1 GiB ESP at /boot — switch to
+  # boot.loader.grub if you're installing on a legacy-BIOS machine.
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
   # Keyboard & language — set by the installer.
   console.keyMap = "$KEYMAP_LAYOUT";
   i18n.defaultLocale = "$LOCALE";