feat(cli): Add fmt command for configuration file formatting

why: Provide consistent formatting for vcspull configuration files
what:
- Create fmt.py module for formatting configuration files
- Convert compact format (string URLs) to verbose format
- Standardize on 'repo' key instead of 'url'
- Sort directories and repositories alphabetically
- Add --write flag to apply changes (dry-run by default)
- Add --all flag to format all discovered config files
- Integrate fmt command into main CLI parser
- Simplify argument passing in CLI module

refs: Part of scanner-and-add feature implementation

Author: tony

src/vcspull/cli/__init__.py

@@ -16,6 +16,7 @@
 
 from .add import add_repo, create_add_subparser
 from .add_from_fs import add_from_filesystem, create_add_from_fs_subparser
+from .fmt import create_fmt_subparser, format_config_file
 from .sync import create_sync_subparser, sync
 
 log = logging.getLogger(__name__)
@@ -93,16 +94,26 @@ def create_parser(
     )
     create_add_from_fs_subparser(add_from_fs_parser)
 
+    fmt_parser = subparsers.add_parser(
+        "fmt",
+        help="format vcspull configuration files",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description="Format vcspull configuration files for consistency. "
+        "Normalizes compact format to verbose format, standardizes on 'repo' key, "
+        "and sorts directories and repositories alphabetically.",
+    )
+    create_fmt_subparser(fmt_parser)
+
     if return_subparsers:
         # Return all parsers needed by cli() function
-        return parser, (sync_parser, add_parser, add_from_fs_parser)
+        return parser, (sync_parser, add_parser, add_from_fs_parser, fmt_parser)
     return parser
 
 
 def cli(_args: list[str] | None = None) -> None:
     """CLI entry point for vcspull."""
     parser, subparsers = create_parser(return_subparsers=True)
-    sync_parser, _add_parser, _add_from_fs_parser = subparsers
+    sync_parser, _add_parser, _add_from_fs_parser, _fmt_parser = subparsers
     args = parser.parse_args(_args)
 
     setup_logger(log=log, level=args.log_level.upper())
@@ -112,34 +123,26 @@ def cli(_args: list[str] | None = None) -> None:
         return
     if args.subparser_name == "sync":
         sync(
-            repo_patterns=args.repo_patterns if hasattr(args, "repo_patterns") else [],
-            config=(
-                pathlib.Path(args.config)
-                if hasattr(args, "config") and args.config
-                else None
-            ),
-            exit_on_error=args.exit_on_error
-            if hasattr(args, "exit_on_error")
-            else False,
+            repo_patterns=args.repo_patterns,
+            config=pathlib.Path(args.config) if args.config else None,
+            exit_on_error=args.exit_on_error,
             parser=sync_parser,
         )
     elif args.subparser_name == "add":
-        add_repo_kwargs = {
-            "name": args.name,
-            "url": args.url,
-            "config_file_path_str": args.config if hasattr(args, "config") else None,
-            "path": args.path if hasattr(args, "path") else None,
-            "base_dir": args.base_dir if hasattr(args, "base_dir") else None,
-        }
-        add_repo(**add_repo_kwargs)
+        add_repo(
+            name=args.name,
+            url=args.url,
+            config_file_path_str=args.config,
+            path=args.path,
+            base_dir=args.base_dir,
+        )
     elif args.subparser_name == "add-from-fs":
-        add_from_fs_kwargs = {
-            "scan_dir_str": args.scan_dir,
-            "config_file_path_str": args.config if hasattr(args, "config") else None,
-            "recursive": args.recursive if hasattr(args, "recursive") else False,
-            "base_dir_key_arg": args.base_dir_key
-            if hasattr(args, "base_dir_key")
-            else None,
-            "yes": args.yes if hasattr(args, "yes") else False,
-        }
-        add_from_filesystem(**add_from_fs_kwargs)
+        add_from_filesystem(
+            scan_dir_str=args.scan_dir,
+            config_file_path_str=args.config,
+            recursive=args.recursive,
+            base_dir_key_arg=args.base_dir_key,
+            yes=args.yes,
+        )
+    elif args.subparser_name == "fmt":
+        format_config_file(args.config, args.write, args.all)