- control/client: TS2021 connection setup — TCP, HTTP CONNECT-style
upgrade to /ts2021, full Noise IK handshake via NoiseStream, then
HTTP/2 client handshake on top via the h2 crate
- control/register: POST /machine/register with pre-auth key, PascalCase
JSON serde matching Tailscale's wire format
- control/netmap: streaming MapStream that reads length-prefixed JSON
messages from POST /machine/map, classifies them into Full/Delta/
PeersChanged/PeersRemoved/KeepAlive, and transparently zstd-decodes
by detecting the 0x28 0xB5 0x2F 0xFD magic (Headscale only compresses
if the client opts in)