Add subcategories

[kutu-dev]

1. Environment

• Device: [Xiaomi Mi11i]
• OS: [Android 14]
• APP: [0.11.1]

2. Describe the feature request

Sometimes you can have a bunch of feeds that are more closely related with eachother than the rest of the category. An example of this are the feeds of The Register, which are organised in two different levels and not be able to collapse the subcategory is tedious and cumbersome.

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