Add COSMIC to xdg-category-names.txt

[jackpot51]

COSMIC is a desktop environment and a valid category name as part of the specification: https://specifications.freedesktop.org/menu-spec/latest/additional-category-registry.html

[jackpot51]

@ximion I would strongly request that the COSMIC category is not filtered out of the metadata as "low quality", we are going to use it to show applications and applets specifically made for the platform.

[razzeee]

I would recommend using keywords

[razzeee]

Related flathub-infra/website#3201

[ximion]

@ximion I would strongly request that the COSMIC category is not filtered out of the metadata as "low quality", we are going to use it to show applications and applets specifically made for the platform.

We will phase out all desktop and toolkit specific categories in the near future, and I am quite against adding even more. If you want to filter things by a project/organization, you can use https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-project_group

[jackpot51]

My concern with project_group is that it only allows one value.

[jackpot51]

We will phase out all desktop and toolkit specific categories in the near future, and I am quite against adding even more

Where is this being discussed? COSMIC is part of the spec now so it does not seem valid to refuse to include it.