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, 22 insertions, 5 deletions

diff --git a/flake.nix b/flake.nix
index 3a8765b..75732a6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,18 +4,33 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
 
+    disko.url = "github:nix-community/disko";
+    disko.inputs.nixpkgs.follows = "nixpkgs";
+
     discidurl.url = "git+https://git.hwebs.info/discidurl?ref=main";
     discidurl.inputs.nixpkgs.follows = "nixpkgs";
   };
 
   outputs =
     { self, nixpkgs, ... }@inputs:
+    let
+      # A machine is common/ + its own machines/<name> module, plus any extra
+      # inline modules (e.g. per-machine overlays).
+      mkMachine =
+        machineModule: extraModules:
+        nixpkgs.lib.nixosSystem {
+          system = "x86_64-linux";
+          specialArgs = { inherit inputs; };
+          modules = [
+            ./common
+            machineModule
+          ]
+          ++ extraModules;
+        };
+    in
     {
-      nixosConfigurations.kusanagi = nixpkgs.lib.nixosSystem {
-        system = "x86_64-linux";
-        modules = [
-          ./configuration.nix
-          ./programs.nix
+      nixosConfigurations = {
+        kusanagi = mkMachine ./machines/kusanagi [
           {
             nixpkgs.overlays = [
               (import ./overlays/haunt.nix)
@@ -23,6 +38,8 @@
             ];
           }
         ];
+
+        enzo = mkMachine ./machines/enzo [ ];
       };
     };
 }