Fix Command class to use args for file detection in tests

The get_added_files() method was using sys.argv to find files, which doesn't
work in test environments where files are passed via args parameter.

Changed to use self.args first (for testing), falling back to sys.argv for
normal hook execution. This fixes test_cfg_files_are_filtered test.

Author: pocc

hooks/utils.py

@@ -37,7 +37,8 @@ def check_installed(self):
 
     def get_added_files(self):
         """Find added files using git."""
-        added_files = sys.argv[1:]  # 1: don't include the hook file
+        # Use self.args if available (for testing), otherwise fall back to sys.argv
+        added_files = self.args[1:] if self.args else sys.argv[1:]
         # cfg files are used by uncrustify and won't be source files
         added_files = [f for f in added_files if os.path.exists(f) and not f.endswith(".cfg")]