(RUF012) Fixed mutable class Defaults- Task 3

[drona-gyawali]

Part of #10196
NOTE: These are NOT automated changes, they are done by hand

This PR addresses Part of RUF012 Rule - Task 3, implementing typing.ClassVar across 4 files with a total of 13 changes. The updates primarily focus on enhancing code quality and resolving linting issues (RUF012) related to mutable class attributes.

Technical

• Updated mutable class attributes in 4 files to use typing.ClassVar for clarity and correctness.
• Added ClassVar annotations to mutable class attributes to ensure they are treated as class-level attributes.
• Ensured proper type hints for clarity and type safety.

Testing

Ran ruff check --select RUF012 to confirm no further warnings.

Screenshot

• N/A

Stakeholders

@RayBB

[RayBB]

Looks great to me but I'll need to get a double check from staff :)

[drona-gyawali]

Hi @RayBB , I made the changes according to your guidance. If there's anything that needs to be modified, please guide me.

[RayBB]

Just one question but otherwise this is on the right path!

[RayBB]

Great work on this one. I think we're ready for @cdrini to take a look.

Testing:

• Adding books to bookshelf worked
• Search autocomplete worked

[scottbarnes]

@drona-gyawali, it may be the case the the tests will pass after rebasing. It may also be the case that it won't help. However, it's likely worth a shot. See Updating your Pull Request if you need any help with that.

[cdrini]

Awesome thank you @drona-gyawali ! Looks good, just a point of feedback around the tuple type hints.

[cdrini]

lgtm! Thank you @drona-gyawali !