Add notifications indicator to header

[creeperkatze]

Adds a notification indicator to the header, replacing the create new button. The popout displays unread notifications with quick actions for managing them directly.

This pr doesnt touch the notifications page on the dashboard, so it would work perfectly even if that was completely reworked in the future.

It uses the SmartClickable component, makes it act similar to the new project card.
I tested it pretty thoroughly with both mock data and real notifications and went to many revisions to make it snappy.

It also uses optimistic updates so api stuff is handled in the background without causing delays.

Aufzeichnung.2026-02-04.210559.mp4

[creeperkatze]

It now works fine with a bunch of notifications, implementing ScrollablePanel

Aufzeichnung.2026-02-04.235319.mp4

[Prospector]

Appreciate the contribution! We have a pretty specific idea in mind for redoing notifications on Modrinth, which goes in some similar directions as this. If you're interested in making some fairly significant changes to fit more what we had in mind, our product director Josh (@Hallskii) can share some mockups and design goals with you if you'd like to help see this through. Regardless, we appreciate the effort!

[creeperkatze]

Appreciate the contribution! We have a pretty specific idea in mind for redoing notifications on Modrinth, which goes in some similar directions as this. If you're interested in making some fairly significant changes to fit more what we had in mind, our product director Josh (@Hallskii) can share some mockups and design goals with you if you'd like to help see this through. Regardless, we appreciate the effort!

Yea, thats understandable for a change like this. I dont have any issues with making significant changes to my design, as im just a student doing this in my free time, its not really a waste of time for me. I would be happy to implement it exactly like the team has it in mind, but if this is handled internally its also fine.

[creeperkatze]

Before reading the comment I also changed up the notification item design a bit to reflect the style of the new project card (#5298).

Not a huge change and has nothing to do with any redesigns, but this is the current state:

Aufzeichnung.2026-02-07.001423.mp4