templates: add minimal clan flake template for (G)UI

templates/flake-module.nix

@@ -1,4 +1,4 @@
-{ self, ... }:
+{ self, inputs, ... }:
 {
   flake.templates = {
     new-clan = {
@@ -10,5 +10,26 @@
       path = ./empty;
     };
     default = self.templates.new-clan;
+    minimal = {
+      description = "for clans managed via (G)UI";
+      path = ./minimal;
+    };
   };
+  flake.checks.x86_64-linux.template-minimal =
+    let
+      path = self.templates.minimal.path;
+      initialized = inputs.nixpkgs.legacyPackages.x86_64-linux.runCommand "minimal-clan-flake" { } ''
+        mkdir $out
+        cp -r ${path}/* $out
+        mkdir -p $out/machines/foo
+        echo '{ "nixpkgs": { "hostPlatform": "x86_64-linux" } }' > $out/machines/foo/settings.json
+      '';
+      evaled = (import "${initialized}/flake.nix").outputs {
+        self = evaled // {
+          outPath = initialized;
+        };
+        clan-core = self;
+      };
+    in
+    evaled.nixosConfigurations.foo.config.system.build.vm;
 }

templates/minimal/flake.nix

@@ -0,0 +1,14 @@
+{
+  inputs.clan-core.url = "git+https://git.clan.lol/clan/clan-core";
+
+  outputs =
+    { self, clan-core, ... }:
+    let
+      # Usage see: https://docs.clan.lol
+      clan = clan-core.lib.buildClan { directory = self; };
+    in
+    {
+      # all machines managed by Clan
+      inherit (clan) nixosConfigurations clanInternals;
+    };
+}