json-line output ignores --time-format rfc3339

[digizeph]

monocle 1.3.0 accepts --time-format rfc3339 on search, but when combined with --format json-line the timestamp field remains a numeric Unix timestamp.

Repro:

monocle search -p 91.105.192.0/23 -s -S -o 18101 \
  -t 1781626459 -d 5m -c rrc14 \
  --format json-line --time-format rfc3339

Observed:

{"timestamp":1781626489.0,...}

Expected: either emit RFC3339 timestamps for JSON/JSONL too, or document that --time-format only applies to non-JSON formats.