When importing a partial export (e.g., only workflows), the import command crashes with an UnboundLocalError.

Steps to reproduce:

1. Export only workflows: cortex backup export -e workflows
2. Try to import: cortex backup import -d /path/to/export
3. Error occurs in _import_catalog()

Error:

UnboundLocalError: cannot access local variable 'results' where it is not associated with a value

Root cause:
The _import_catalog() function (and likely other import functions) doesn't initialize results and failed_count variables before the if os.path.isdir(directory): check. When the catalog directory doesn't exist in a partial export, these variables are referenced without being defined.

Expected behavior:
Import should gracefully handle missing directories and only import what exists in the export.

Files to modify:

• cortexapps_cli/commands/backup.py - All _import_* functions need to initialize results and failed_count before the directory existence check