Restructure into a multi-machine flake and add the enzo laptop

Split the single-host config into a shared minimal base plus opt-in
profiles, and add a second machine (enzo laptop) alongside kusanagi.

- flake: add mkMachine helper; declare nixosConfigurations.kusanagi and
  .enzo; add the disko input; move overlays per-machine.
- common/: minimal base only (boot, networking, tailscale, locale, nix
  settings, neovim editor). Old configuration.nix/programs.nix removed.
- profiles/: coarse opt-in bundles (desktop, dev, apps). kusanagi imports
  all three and stays byte-for-byte identical to the running system.
- machines/kusanagi/: all workstation-only config (ROCm, Scarlett audio,
  optical-disc archiving, NAS mounts, kavita/immich/ollama); hardware
  config moved here unchanged. User stays 'henz'.
- machines/enzo/: new laptop. Declarative LUKS+btrfs via disko
  (LVM-on-LUKS, TPM2+PIN unlock, zram + encrypted swap for
  suspend-then-hibernate); its own minimal niri desktop with
  playback-only audio (no rtkit/jack); user 'hwebs'.

Assisted-by: Claude:claude-opus-4-8

1 files changed, 53 insertions, 0 deletions

diff --git a/common/core.nix b/common/core.nix
new file mode 100644
index 0000000..5d36646
--- /dev/null
+++ b/common/core.nix
@@ -0,0 +1,53 @@
+# Boot, networking, locale, and Nix settings shared by all machines.
+{ pkgs, ... }:
+
+{
+  # Editor available on every machine (even a headless one).
+  environment.systemPackages = [ pkgs.neovim ];
+  programs.neovim = {
+    enable = true;
+    defaultEditor = true;
+  };
+
+  # Bootloader.
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  # Enable networking
+  networking.networkmanager.enable = true;
+
+  # for tailscale
+  networking.firewall.trustedInterfaces = [ "tailscale0" ];
+  networking.firewall.allowedUDPPorts = [ 41641 ];
+  services.tailscale.enable = true;
+
+  # Set your time zone.
+  time.timeZone = "America/Chicago";
+
+  # Select internationalisation properties.
+  i18n.defaultLocale = "en_US.UTF-8";
+
+  i18n.extraLocaleSettings = {
+    LC_ADDRESS = "en_US.UTF-8";
+    LC_IDENTIFICATION = "en_US.UTF-8";
+    LC_MEASUREMENT = "en_US.UTF-8";
+    LC_MONETARY = "en_US.UTF-8";
+    LC_NAME = "en_US.UTF-8";
+    LC_NUMERIC = "en_US.UTF-8";
+    LC_PAPER = "en_US.UTF-8";
+    LC_TELEPHONE = "en_US.UTF-8";
+    LC_TIME = "en_US.UTF-8";
+  };
+
+  # trusted-users is set per-machine (see machines/<host>/default.nix).
+
+  nix.settings.experimental-features = [
+    "nix-command"
+    "flakes"
+  ];
+
+  # Allow unfree packages
+  nixpkgs.config.allowUnfree = true;
+
+  environment.localBinInPath = true;
+}