feat(categories): Add customizable button styles

[Daste745]

Versioning information

• This includes major changes (breaking changes)
• This includes minor changes (minimal usage changes, minor new features)
• This includes patches (bug fixes)
• This does not change functionality at all (code refactoring, comments)

Is this related to an issue?

Changes made

This change allows the user to select the category button style displayed in panels instead of always using Secondary (2). Adding colors to buttons makes it easier to distinguish between and direct users to the correct ticket category.

Example screenshot (panel with 4 categories):

Confirmations

• I have updated related documentation (if necessary) - Add section about category button styles docs#56
• My changes use consistent code style
• My changes have been tested and confirmed to work

[Daste745]

CI is failing on migrations. I can remove them if you want to create migration files separately from this PR.

[Daste745]

@eartharoid could you please take a quick look at this? If there are any changes I need to make before this is merged please let me know.

I think this would be a nice-to-have feature also for other users. I'm pinging just because this has been inactive since ~3mo.