Retry on empty addition - #702

This PR implements a robust retry mechanism for empty additions in the CLI. Key changes:

• Updated retry module to detect empty diffs and automatically retry the operation up to 3 times.
• Added unit tests in tests/test_retry.py covering:
  • Successful retry when the first attempt fails due to no changes.
  • Failure after maximum retries.
  • Correct handling of non-empty diffs.
• Updated documentation in docs/cli.md to explain the new retry behavior.
• Minor refactor of the add command to use the new retry logic.

The PR addresses issue #67 and ensures that the CLI does not exit with an error when no changes are detected. Please review the changes and run the CI pipeline to confirm the retry logic works as expected.

Implementation notes:

• The retry logic is now encapsulated in src/cli/retry.py.
• Tests use the pytest framework and the click.testing module.
• The PR targets the main branch of the upstream cecli-dev/cecli repository.

Thank you for reviewing!