Fix ImportError: Add missing up() function to up.py

The up.py module was missing the up() function that serves as a
backward-compatible alias for run(). This caused an ImportError when
the commands/__init__.py tried to import 'up' from the module.

Added the up() function following the same pattern used in other
command modules (down.py, bootstrap.py) to resolve the import issue.

Fixes the traceback:
  ImportError: cannot import name 'up' from 'devman.commands.up'

Author: claude

src/devman/commands/up.py

@@ -119,3 +119,8 @@ def _load_nvim_session(config: WorkspaceConfig) -> None:
 
     for command in NVIM.build_session_commands(config.root, session_path):
         NVIM.remote_send(config.nvim_listen, command)
+
+
+def up(root: Path | None = None) -> WorkspaceConfig:
+    """Backward-compatible alias for run."""
+    return run(root=root)