refactor: remove Machine.vars_generators() method

Replace all calls to machine.vars_generators() with direct calls to
Generator.generators_from_flake() to make the dependency more explicit
and remove unnecessary indirection.

This reduces coupling to the Machine class, making the codebase more
modular and easier to refactor in the future.

pkgs/clan-cli/clan_cli/vars/fix.py

@@ -9,7 +9,9 @@ log = logging.getLogger(__name__)
 
 
 def fix_vars(machine: Machine, generator_name: None | str = None) -> None:
-    generators = machine.vars_generators()
+    from clan_cli.vars.generate import Generator
+
+    generators = Generator.generators_from_flake(machine.name, machine.flake, machine)
     if generator_name:
         for generator in generators:
             if generator_name == generator.name: