fix(theme): category quantity input value omitted when adding product to cart

[sethidden]

Description

Fixed the reported issue where adding items from the list view would add them to cart always with quantity 1, even if the user provided something else eg. 1337

Since it's a change to business logic I really wanted to write some tests for this, but there's a lot of boilerplate code to even start (which would turn this 5 min task into a 6 hour one)

Also fixed some linting errors as husky started bothering me because I touched the file

Related Issue

#662

How Has This Been Tested?

Tested manually the two scenarios:

1. Add many products to cart (e.g. 1337)
2. Add one (to check if the value "null" is not emitted or something when there's just 1 - there's not)

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.