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>

README.md

@@ -58,7 +58,9 @@ Flat on purpose. Two module trees, one options file each, no hidden layers.
 ├── hosts/
 │   ├── default/                   # reference machine (thin: boot, user, hostname)
 │   └── live.nix                   # bootable live ISO (try the distro, no install)
-├── pkgs/nomarchy-theme-sync/      # state writer + rebuild dispatcher (Python)
+├── pkgs/
+│   ├── nomarchy-theme-sync/       # state writer + rebuild dispatcher (Python)
+│   └── nomarchy-install/          # live-ISO installer (gum + disko + mkFlake)
 ├── templates/downstream/          # `nix flake init -t` starter for users
 ├── docs/TESTING.md                # how to verify changes (incl. AI-agent rules)
 └── tools/                         # maintainer-only
@@ -86,6 +88,17 @@ the locked inputs into the ISO store — so theme switching (including the
 `home-manager switch` it triggers) works **offline**, exactly like on an
 installed system. Verification checklist: [docs/TESTING.md](docs/TESTING.md).
 
+Like what you see? **`nomarchy-install`** (in a terminal) walks you through
+installing to disk: pick a disk, optional LUKS2 full-disk encryption, user +
+hostname + timezone, hardware autodetection (DMI → nixos-hardware profile),
+then disko partitions (GPT + ESP + BTRFS subvolumes) and `nixos-install`
+runs — **without a network** when the ISO was built from a clean tree (the
+target's `flake.lock` is composed from the rev the ISO carries). The
+installed machine gets the standard downstream layout: the flake at
+`~/.nomarchy` (`/etc/nixos` symlinks to it), one `mkFlake` call, your
+`system.nix`/`home.nix`. First boot lands in the fully themed desktop —
+the installer pre-activates the Home Manager generation. UEFI only for now.
+
 ## 3. Using Nomarchy on your machine (downstream)
 
 Nomarchy is consumed as a flake input — you never fork or edit this repo:
@@ -112,7 +125,7 @@ outputs = { nomarchy, ... }:
 |---|---|---|
 | `src` | — (required) | Your flake directory (`./.`) |
 | `username` | — (required) | Login name; flows into `system.nix` and names the HM config |
-| `hardwareProfile` | `null` | A [nixos-hardware](https://github.com/NixOS/nixos-hardware) module name (pinned + tested by Nomarchy; unknown names fail with suggestions) |
+| `hardwareProfile` | `null` | One [nixos-hardware](https://github.com/NixOS/nixos-hardware) module name, or a list of them (pinned + tested by Nomarchy; unknown names fail with suggestions) |
 | `system` | `"x86_64-linux"` | Platform |
 
 (Power users can skip `mkFlake` and wire `nixosModules.nomarchy` /
@@ -216,6 +229,6 @@ workspaces · `Print` region screenshot.
   re-copy on every state write is the main eval tax), then pre-built theme
   variants if still needed
 - Plymouth + SDDM/greeter theming from the same JSON
-- Interactive installer on the live ISO (disko BTRFS+LUKS, DMI →
-  `hardwareProfile` autodetection feeding `mkFlake`) — port from old_distro
+- Installer round 2: multi-disk BTRFS RAID, impermanence, BIOS/legacy
+  boot (v1 `nomarchy-install` is single-disk UEFI — see `pkgs/nomarchy-install`)
 - `hyprlock`/`hypridle`, swayosd, launch-or-focus UX scripts