vars: make all python tests work in nix sandbox

- generate a flake.lock file for each template by copying the clan-core flake.lock and modifying it

- call nix build with --store for tests inside the sandbox

templates/minimal-flake-parts/flake.nix

@@ -1,10 +1,10 @@
 {
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
 
-    clan.url = "git+https://git.clan.lol/clan/clan-core";
-    clan.inputs.nixpkgs.follows = "nixpkgs";
-    clan.inputs.flake-parts.follows = "flake-parts";
+    clan-core.url = "https://git.clan.lol/clan/clan-core/archive/main.tar.gz";
+    clan-core.inputs.nixpkgs.follows = "nixpkgs";
+    clan-core.inputs.flake-parts.follows = "flake-parts";
 
     flake-parts.url = "github:hercules-ci/flake-parts";
     flake-parts.inputs.nixpkgs-lib.follows = "nixpkgs";

templates/minimal/flake.nix

@@ -1,5 +1,6 @@
 {
-  inputs.clan-core.url = "git+https://git.clan.lol/clan/clan-core";
+  inputs.clan-core.url = "https://git.clan.lol/clan/clan-core/archive/main.tar.gz";
+  inputs.nixpkgs.follows = "clan-core/nixpkgs";
 
   outputs =
     { self, clan-core, ... }:

templates/new-clan/flake.nix

@@ -2,6 +2,7 @@
   description = "<Put your description here>";
 
   inputs.clan-core.url = "https://git.clan.lol/clan/clan-core/archive/main.tar.gz";
+  inputs.nixpkgs.follows = "clan-core/nixpkgs";
 
   outputs =
     { self, clan-core, ... }: