- Move `util/grpc` and `util/net` to `client` so `internal` packages can be accessed
- Add methods to return the next best interface after the NetBird interface.
- Use `IP_UNICAST_IF` sock opt to force the outgoing interface for the NetBird `net.Dialer` and `net.ListenerConfig` to avoid routing loops. The interface is picked by the new route lookup method.
- Some refactoring to avoid import cycles
- Old behavior is available through `NB_USE_LEGACY_ROUTING=true` env var
This PR adds user approval functionality to the management system, allowing administrators to manually approve new users joining via domain matching. When enabled, users are blocked with pending approval status until explicitly approved by an admin.
Adds UserApprovalRequired setting to control manual user approval requirement
Introduces user approval and rejection endpoints with corresponding business logic
Prevents pending approval users from adding peers or logging in
