fix(cli): remove invalid --cwd flag config and make upgrade a proper alias

- Remove is_flag=False + flag_value="." combination which has no effect
  on click option with is_flag=False (default)
- Create dedicated click.Command for upgrade instead of raw alias
  assignment, so help shows correct command name

bin/commands/__init__.py

@@ -1,8 +1,13 @@
 """CLI subcommands."""
 
+import click
+
 from .update import update_cmd
 
-# alias: upgrade is the same as update
-upgrade_cmd = update_cmd
-
 __all__ = ["update_cmd", "upgrade_cmd"]
+
+
+@click.command("upgrade")
+def upgrade_cmd() -> None:
+    """Alias for update: reinstall myclaude from this repository."""
+    return click.get_current_context().invoke(update_cmd)