[Feature] Pre-auth keys without user binding & group tagged devices

[alirezamirsepassi]

Use case

It would be super helpful if we could create pre-auth keys without having to bind them to a specific user. This would make the setup process a lot more flexible and align with how Tailscale does it. Sometimes, you just want to provision devices without worrying about assigning them to users upfront.

Also, in the interface, it’d be awesome to have all tagged devices grouped under a "Tagged Devices" section. This would make things much cleaner and easier to navigate, especially when you’re managing a lot of nodes. It just feels like a natural way to organize them.

Description

1. Pre-auth keys without user binding: Add a way to generate pre-auth keys that don’t require a user assignment. This gives more freedom when onboarding devices, especially for shared or temporary setups.

2. Group tagged devices: Update the interface to show a dedicated "Tagged Devices" section. It’s a small change, but it would make finding and managing tagged devices so much simpler.

Contribution

• I can write the design doc for this feature
• I can contribute this feature

How can it be implemented?

• For pre-auth keys: Update the backend logic and the database schema so keys can be created without linking them to a user.

• For grouping tagged devices: In the function that returns the user profile, check if the node is tagged; if so, use "Tagged Devices" as DisplayName

[kradalby]

Sounds related/overlapping to #1369