Pilot Potential 6-Week long Packet

Close this issue if discussion moves against trying this, but there is discussion of changing packet to last for all six weeks and close for frosh as they hit 60%, so i'd love to see a branch that implements this so we can test it out for a semester and revert if we hate it.

See https://cshrit.slack.com/archives/CV0REE4JE/p1773708892372929 for discussion thread.

未指定任何文件、测试或入口点。先检查现有的 packet 生命周期和链接的 Slack 讨论，然后确定为期六周的 packet 以及 60% 的 frosh-closing 规则如何与当前行为相适配。完成的标准是：有一个可测试的 branch 实现提议的 pilot，同时不会掩盖如何将其还原。

由索引模型根据 Issue 内容生成。