* Plumb disablement values through some of the internals of TKA enablement.
* Transmit the node's TKA hash at the end of sync so the control plane understands each node's head.
* Implement /machine/tka/disable RPC to actuate disablement on the control plane.
There is a partner PR for the control server I'll send shortly.
Signed-off-by: Tom DNetto <tom@tailscale.com>
Tom DNetto
Josh Soref
Adrian Dewhurst