Summary

Two issues with backup command error handling:

1. cortex backup import exits with return code 0 even when it fails (e.g., with invalid API key)
2. cortex backup export prints ugly Python stack trace on failure (though it does exit non-zero)

Reproduction

# Test with invalid API key
CORTEX_API_KEY=invalid cortex backup import -d /some/path
echo $?  # Returns 0 (should be non-zero)

CORTEX_API_KEY=invalid cortex backup export -d /some/path
# Prints stack trace (should be clean error message)

Tasks

• Add test for backup import with invalid API key, verify non-zero exit
• Fix backup import to exit non-zero on failure
• Fix backup export to suppress stack trace on failure
• Add test for backup export error handling