Simplify installer into shared common.nix + per-platform targets

Replaces the single monolithic installer.nix (preserved as
installer_old.nix for reference) with a shared common.nix carrying the
install-script/user/SSH baseline, consumed by per-platform targets
(installer.nix for netboot/ISO, new proxmox-lxc.nix for the Proxmox
LXC-based flow). flake.nix drops the nixos-generators input in favor
of building images directly from each nixosConfiguration's
system.build.isoImage/tarball.

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

flake.nix

@@ -1,68 +1,113 @@
-# flake.nix
 {
   description = "Auto-install NixOS ISO";
 
   inputs = {
-#    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
+
     nixos-conf-editor.url = "github:snowfallorg/nixos-conf-editor";
+
     flake-utils.url = "github:numtide/flake-utils";
-    nixos-generators = {
-      url = "github:nix-community/nixos-generators";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
-    # home-manager.url = "github:nix-community/home-manager";
-    # home-manager.inputs.nixpkgs.follows = "nixpkgs";
+
     home-manager = {
       url = "github:nix-community/home-manager/release-26.05";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
     disko = {
       url = "github:nix-community/disko";
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };
 
-  outputs = { self, nixpkgs, flake-utils, nixos-generators, home-manager, ... }:
-    flake-utils.lib.eachDefaultSystem (system:
-      let
-        pkgs = nixpkgs.legacyPackages.${system};
 
-        iso = nixos-generators.nixosGenerate {
-          inherit system;
-          format = "install-iso";
-          modules = [
-            ./installer.nix
+  outputs = { self, nixpkgs, flake-utils, home-manager, ... }:
+
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+
+      netbootSystem = nixpkgs.lib.nixosSystem {
+        inherit system;
+
+        modules = [
+          ./installer.nix
+
+          ({ modulesPath, ... }: {
+            imports = [
+              (modulesPath + "/installer/netboot/netboot-minimal.nix")
+            ];
+          })
+        ];
+      };
+
+
+    in
+    {
+
+      #
+      # Complete NixOS systems
+      #
+      # These can be used with:
+      #
+      # nixos-rebuild switch --flake .#name
+      #
+
+      nixosConfigurations = {
+
+        installer =
+          nixpkgs.lib.nixosSystem {
+            inherit system;
+
+            modules = [
+              ./installer.nix
+            ];
+          };
+
+
+        proxmox-lxc =
+          nixpkgs.lib.nixosSystem {
+            inherit system;
+
+            modules = [
+              ./proxmox-lxc.nix
+            ];
+          };
+
+      };
+
+
+      #
+      # Buildable artifacts
+      #
+      # These are built with:
+      #
+      # nix build .#name
+      #
+
+      packages.${system} = {
+
+        netboot-ipxe =
+          netbootSystem.config.system.build.netbootIpxeScript;
+
+
+        netboot-initrd =
+          netbootSystem.config.system.build.netbootRamdisk;
+
+
+        netboot-kernel =
+          netbootSystem.config.system.build.kernel;
+        images =
+          pkgs.linkFarm "images" [
+            {
+              name = "installer-iso";
+              path = self.nixosConfigurations.installer.config.system.build.isoImage;
+            }
+            {
+              name = "proxmox-lxc";
+              path = self.nixosConfigurations.proxmox-lxc.config.system.build.tarball;
+            }
           ];
-        };
+      };
 
-netbootSystem = nixpkgs.lib.nixosSystem {
-  inherit system;
-
-  modules = [
-    ./installer.nix
-
-    ({ modulesPath, ... }: {
-      imports = [
-        (modulesPath + "/installer/netboot/netboot-minimal.nix")
-      ];
-    })
-  ];
-};
-      in {
-        packages.default = iso;
-
-#        packages.netboot = netbootSystem.config.system.build.netboot;
-
-#packages.netboot-debug =
-#  pkgs.writeText "attrs.json"
-#    (builtins.toJSON
-#      (builtins.attrNames netbootSystem.config.system.build));
-
-packages.netboot-ipxe = netbootSystem.config.system.build.netbootIpxeScript;
-packages.netboot-initrd = netbootSystem.config.system.build.netbootRamdisk;
-packages.netboot-kernel = netbootSystem.config.system.build.kernel;
-
-
-      });
-}
+    };
+}