fix: stale comment in cohort mutual-exclusivity guard (cli.py:1791)

[decko]

Finding

In src/raki/cli.py:1791, a code comment says:

# --- Mutual exclusivity: --since and --group-by cannot be used together ---

However, the surrounding block was updated (in PR #340) to also enforce --until/--group-by mutual exclusivity. The comment no longer reflects reality and may confuse future contributors.

Suggested Fix

Update the comment to:

# --- Mutual exclusivity: --since/--until and --group-by cannot be used together ---

References

• Found during review of fix(cli): raise UsageError for --until + --group-by before session loading #340 (fix: --until silently ignored when combined with --group-by in cohort command)
• Related ticket: fix: --until silently ignored when combined with --group-by in cohort command #318