fix: Update dayjs configuration after modifying the start day of the week

[haydenull]

Hello, thank you for your PR (haydenull#296). I finally have time to work on it.​

Since it's hard to describe in words, I made a new commit. I'm not very familiar with open source collaboration, so if this approach is not reasonable, please feel free to let me know your thoughts.​

Here are some suggested changes:​

1. Since the dayjs library previously had logic for setting the start of the week and used number types, I unified the related types to number.​
2. Update dayjs configuration after modifying the start of the week.​
3. Modify how default values are handled.

[e-zz]

Hi, great to have you back! You're doing it perfectly. I've just merged the changes, and now it's ready for shipping.
Thanks!