Change a single Tailscale preference incrementally with tailscale set without resetting others

Documented steps

1. Confirm you are already logged in/up, then run `tailscale set` with only the flags you want to change (no default values are applied — only what you pass is updated).
2. Common options: --hostname=<name> to rename the node; --ssh to enable/disable the Tailscale SSH server; --accept-routes (or =false) to accept subnet routes other nodes advertise; --advertise-routes=<ip>,<ip> (or empty) to advertise this node as a subnet router; --advertise-exit-node to offer this node as an exit node.
3. Select an exit node without the cumbersome exit-node flag on up: `tailscale set --exit-node=<ip-or-name>`; clear it with `tailscale set --exit-node=`. You can also use --exit-node=auto:any to track the suggested exit node automatically.
4. Control DNS: `tailscale set --accept-dns=false` to stop accepting admin-console DNS/MagicDNS settings (e.g. on Linux where you want system DNS to manage resolution, or on servers).
5. Toggle auto-updates: `tailscale set --auto-update` (or =false).
6. Inspect what is currently configured with `tailscale get` (shows the current preference values), or `tailscale debug prefs` for the full state.
7. On Linux you may need operator rights: `sudo tailscale set --operator=$USER` to allow the current user to run tailscale set without sudo.