Revert "templates: remove .clan-flake"

This reverts commit 14eb541256.

pkgs/clan-cli/clan_cli/tests/test_create_flake.py

@@ -23,6 +23,7 @@ def test_create_flake(
 
     cli.run(["flakes", "create", str(flake_dir), "--template=default", "--no-update"])
 
+    assert (flake_dir / ".clan-flake").exists()
     # Replace the inputs.clan-core.url in the template flake.nix
     substitute(
         flake_dir / "flake.nix",
@@ -60,6 +61,7 @@ def test_create_flake_existing_git(
 
     cli.run(["flakes", "create", str(flake_dir), "--template=default", "--no-update"])
 
+    assert (flake_dir / ".clan-flake").exists()
     # Replace the inputs.clan-core.url in the template flake.nix
     substitute(
         flake_dir / "flake.nix",