Add a Database Reco Counts report command #2442

Summary

VWS can generate a per-database recognition counts report: a request for a given YYYY-mm month returns a presigned URL which serves a CSV report (target_id,reco_count) once generation has finished. The CLI has no command for this, and it suits a CLI well — a single command can request the report, wait for it, and write the CSV to a file or stdout.

This is blocked on client support in vws-python (VWS-Python/vws-python#3134). vws-python-mock implements the endpoint, including the generation delay, the 404 served while the report is not ready, and month and database ID validation, so the command can be tested end to end.

Suggested scope

• Add a command which requests a reco counts report for a database and a month.
• Wait for the report to become available, and write the CSV to a given path or to stdout.
• Add an option to skip waiting and print the presigned URL instead.
• Follow the existing option and environment-variable conventions for credentials and the base URL.
• Map the invalid-month, out-of-range-month and unknown-database errors to useful exit codes and messages in _error_handling.py.
• Add documentation, shell-completion coverage and a news fragment.

Acceptance criteria

• The command requests, waits for and downloads a report.
• Tests exercise the command against vws-python-mock, including a report which is not immediately available and the documented validation failures.
• Documentation and --help output describe the new command and its options.