линтеры python перенастроены: mypy заменён на pyrefly

- набор правил ruff расширен по канону rp-local-env (ANN, PTH, C90, G и др.),
  в lefthook добавлен job ruff check --fix
- код приведён под новые правила: логирование через %s вместо f-строк,
  os.path заменён на pathlib, run_backup_process и initialize разбиты
  на функции по порогу цикломатической сложности

files/keep-files.py

@@ -1,7 +1,8 @@
 #!/usr/bin/env python3
 
-import os
 import argparse
+import os
+from pathlib import Path
 
 
 def main() -> None:
@@ -18,12 +19,13 @@ def main() -> None:
     if args.keep < 0:
         parser.error("--keep value cannot be negative")
 
-    if not os.path.isdir(args.directory):
+    directory = Path(args.directory)
+    if not directory.is_dir():
         parser.error(f"Directory not found: {args.directory}")
 
     # Get list of files (exclude subdirectories)
     files = []
-    with os.scandir(args.directory) as entries:
+    with os.scandir(directory) as entries:
         for entry in entries:
             if entry.is_file():
                 files.append(entry.name)
@@ -36,9 +38,9 @@ def main() -> None:
 
     # Delete files and print results
     for filename in to_delete:
-        filepath = os.path.join(args.directory, filename)
+        filepath = directory / filename
         try:
-            os.remove(filepath)
+            filepath.unlink()
             print(f"Deleted: {filename}")
         except Exception as e:
             print(f"Error deleting {filename}: {str(e)}")