clan-cli: initialize python project from template

clan-cli: remove unnecessary unit test file

clan-cli: fix shell.nix too stateful

clan-cli: remove conftest.py

clan-cli: fix flake-module.nix

pkgs/clan-cli/shell.nix

@@ -0,0 +1,47 @@
+{ pkgs ? import <nixpkgs> { }
+, system ? builtins.currentSystem
+,
+}:
+let
+  lib = pkgs.lib;
+  python3 = pkgs.python3;
+  package = import ./default.nix {
+    inherit lib python3;
+  };
+  pythonWithDeps = python3.withPackages (
+    ps:
+    package.propagatedBuildInputs
+    ++ package.devDependencies
+    ++ [
+      ps.pip
+    ]
+  );
+  checkScript = pkgs.writeScriptBin "check" ''
+    nix build -f . tests.check -L "$@"
+  '';
+  devShell = pkgs.mkShell {
+    packages = [
+      pkgs.ruff
+      pythonWithDeps
+    ];
+    # sets up an editable install and add enty points to $PATH
+    shellHook = ''
+      tmp_path=$(realpath ./.pythonenv)
+      repo_root=$(realpath .)
+      rm -rf $tmp_path
+      mkdir -p "$tmp_path/${pythonWithDeps.sitePackages}"
+
+      ${pythonWithDeps.interpreter} -m pip install \
+        --quiet \
+        --disable-pip-version-check \
+        --no-index \
+        --no-build-isolation \
+        --prefix "$tmp_path" \
+        --editable $repo_root
+
+      export PATH="$tmp_path/bin:${checkScript}/bin:$PATH"
+      export PYTHONPATH="$repo_root:$tmp_path/${pythonWithDeps.sitePackages}"
+    '';
+  };
+in
+devShell