fix: 🐛 fix chain_second_seq bug when sequence length gte 200

[nothing2sayi]

No description provided.

[reneleonhardt]

Could you explain what this pull request changes?
I see a bugfix and two features.

[nothing2sayi]

Could you explain what this pull request changes?能否解释一下此 Pull Request 更改了什么？ I see a bugfix and two features.我看到了一个漏洞修复以及两个新功能。

Hi @reneleonhardt,

Sorry for the delay! Here is a breakdown of what this PR includes:

Bugfix & Refactor:

Fixed an issue in chain_second_seq when the sequence length is greater than or equal to 200.

Replaced raw tags with an Enum to improve type safety and readability.

Features:

Added an as_str method for Tag for easier string representation.

Added the quick_ratio function for faster calculation of sequence similarity ratio.

Let me know if you need any adjustments!

[reneleonhardt]

I'm no maintainer, but I find your contribution valuable!

For me personally, I don't understand why you left a commented block, and if possible the fix should be separated from the enum: fix, enum, feature commits.
That would make it easier to review in my eyes.

In addition, I don't understand why there are no unit tests for your new methods, bugfixes and features. Did you check coverage before and after?