Adding log rotation using lumberjack

[sergey3bv]

@YusukeShimizu
@nepet
Addressing #301

[YusukeShimizu]

Thank you for the log rotation update; this is a valuable improvement overall.
I have one concern that looks blocking, so I’m marking this as request changes for now and would appreciate a quick confirmation.

[sergey3bv]

Hey, @YusukeShimizu, I updated the PR accordingly, could you please review it? Also are there any issues I can help with?

[YusukeShimizu]

Thanks for addressing the earlier feedback and improving the log rotation overall!

If my understanding is correct, there are two points we might need to address before merging:

1. Existing nodes currently use /log as a file, but it looks like this PR changes the same path into a directory. Please correct me if I'm wrong, but wouldn't this cause an in-place upgrade to fail at startup? We might need to add a migration step for the old file or keep the path backward-compatible.

2. It seems logrotation.maxsize, maxbackups, and maxage are being accepted without validation. I'm concerned that invalid values (especially maxsize <= 0) could silently break file logging rather than failing fast at startup.

Let me know your thoughts on this!

[sergey3bv]

1. Existing nodes currently use /log as a file

As I am thinking about it now we can leave the current flow and store rotated logs nearby. For example, logs will still be written in log and rotated ones will be in rotated_logs or even in user provided location. This way PR will produce less friction, what do you think?

[sergey3bv]

2. I'm concerned that invalid values (especially maxsize <= 0) could silently break file logging

Good point, I will fix it right away

[YusukeShimizu]

That sounds like a good direction to me. Keeping the active log at the current /log path would avoid the upgrade compatibility issue, and it should reduce friction for existing deployments.