Previously the selected --tail value only trimmed the initial log
snapshot; since logs are followed live afterwards, the view kept
growing unbounded past the chosen count. Now the main panel writer
re-truncates to the last N lines on every new line, so e.g. tail: 50
always shows only the 50 most recent lines. Behavior when
following logs to stdout (the 'm' keybinding) is unchanged, matching
plain `docker logs --tail N -f` there.
Lets you press 't' while focused on the containers panel to cycle
through common --tail presets (all, 50, 100, 200, 500) for the
selected container's Logs tab, instead of only being able to set a
fixed value via the logs.tail config option. The current value is
shown in the Logs tab subtitle.
