fix(entrypoint): /home/lftp/.lftp-logs grows unbounded across runs

gh issue create --title "fix(entrypoint): /home/lftp/.lftp-logs grows unbounded across runs" --label "bug,audit,priority:medium" --body "## Finding

lftp writes debug logs to \$HOME/.lftp-logs (when debug is enabled). The action runs in a fresh container per job, so within a single run the logs are bounded; but on a self-hosted runner with a persistent HOME, the directory accumulates across runs. No rotation, no cleanup.

## Affected code

- entrypoint.sh — lftp invocation does not rotate or clean \$HOME/.lftp-logs

## Reproduction

1. Run the action many times on a self-hosted runner with persistent HOME.
2. Inspect /home/lftp/.lftp-logs: file count grows unbounded.

## Suggested fix

Either:
- Add a rotate step at the start of entrypoint.sh that keeps the last N log files (e.g. find \$HOME/.lftp-logs -type f -mtime +7 -delete).
- Or document that \$HOME should be ephemeral on self-hosted runners.
- Or set lftp's debug-level to a value that does not write to disk by default.

The first option is the cleanest.

## Source

F2 audit 2026-09-03 (entrypoint.sh audit). Reporter: subagent-pekodbj7.

## Related

- Part of EPIC #[epic-number]
- Closes: #NONE (no existing issue)"