feat: nomarchy-install — guided live-ISO installer (disko + mkFlake)

Ported from the previous iteration's installer (3bdfc35), adapted to the
mkFlake world. gum TUI: disk pick, optional LUKS2, user/hostname/timezone,
DMI → nixos-hardware autodetection (hardware-db.sh). disko partitions
GPT + 1 GiB ESP + BTRFS subvolumes; the generated machine flake lands at
~user/.nomarchy (one mkFlake call, /etc/nixos symlinks to it) and
nixos-install makes it bootable (UEFI/systemd-boot, v1 single disk).

Offline by construction: the target flake.lock is composed from the rev
the ISO was built from (compose-lock.py), `nix flake archive` seeds the
target store, and the ISO pre-builds the template system + desktop.
First boot lands themed: the HM generation is pre-activated in chroot.

mkFlake grows two things for this: hardwareProfile now also takes a list
(autodetection emits several common-* modules), and installed systems get
the standalone home-manager CLI from the pinned input. Unattended mode
(NOMARCHY_UNATTENDED=1 + env) documented in docs/TESTING.md §4.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pkgs/nomarchy-install/disko-config.nix

@@ -0,0 +1,70 @@
+# Nomarchy installer disk layout — single disk, GPT, 1 GiB ESP, BTRFS
+# root with subvolumes, optionally under LUKS2. Invoked by
+# nomarchy-install via:
+#
+#   disko --mode destroy,format,mount \
+#         --argstr mainDrive /dev/nvme0n1 \
+#         --arg    withLuks true \
+#         disko-config.nix
+#
+# Ported from the previous iteration's golden-path config (multi-disk
+# RAID and the impermanence snapshot dropped for v1 — see git history
+# of installer/disko-config.nix at 3bdfc35 when adding them back).
+# Function arguments, not sed-templating: escaping shell into Nix
+# proved fragile twice before.
+{ mainDrive
+, withLuks ? true
+, ...
+}:
+
+let
+  btrfsMountOptions = [ "compress=zstd" "noatime" ];
+
+  rootBtrfs = {
+    type = "btrfs";
+    extraArgs = [ "-f" ];
+    subvolumes = {
+      "@" = { mountpoint = "/"; mountOptions = btrfsMountOptions; };
+      "@home" = { mountpoint = "/home"; mountOptions = btrfsMountOptions; };
+      "@nix" = { mountpoint = "/nix"; mountOptions = btrfsMountOptions; };
+      "@log" = { mountpoint = "/var/log"; mountOptions = btrfsMountOptions; };
+    };
+  };
+in
+{
+  disko.devices.disk.main = {
+    type = "disk";
+    device = mainDrive;
+    content = {
+      type = "gpt";
+      partitions = {
+        # 1 GiB ESP — fits several kernel generations + initrd.
+        ESP = {
+          priority = 1;
+          name = "ESP";
+          start = "1M";
+          end = "1G";
+          type = "EF00";
+          content = {
+            type = "filesystem";
+            format = "vfat";
+            mountpoint = "/boot";
+            mountOptions = [ "umask=0077" ];
+          };
+        };
+        root = {
+          size = "100%";
+          content =
+            if withLuks then {
+              type = "luks";
+              name = "crypted";
+              passwordFile = "/tmp/nomarchy-luks.key";
+              settings.allowDiscards = true;
+              content = rootBtrfs;
+            } else
+              rootBtrfs;
+        };
+      };
+    };
+  };
+}