Keep the iPhone's name out of its tailnet hostname

docs/iphone.md

@@ -17,5 +17,5 @@ The simulator's window (Xcode's Device Hub) lists the app's own accessibility el
 ## Platform facts
 
 - CloudKit on iOS requires the `remote-notification` background mode in `Info.plist`, even though the app sets up no push of its own.
-- The phone's tailnet node and `Byre-Host` take its name from `UIDevice.current.name`, which iOS reads only on the main actor (so the app delegate reads it first) and returns as just `iPhone` unless the app has the `com.apple.developer.device-information.user-assigned-device-name` entitlement. Apple grants that entitlement on request (developer.apple.com/contact/request/user-assigned-device-name); it then has to be enabled on the App ID and added to `mac/phone/byre.entitlements`. The simulator returns the simulator device's own name without it.
+- The phone's tailnet node is always `byre-app-iphone`; the phone's own name stays inside byre. `Byre-Host`, which the server shows for the phone, takes its name from `UIDevice.current.name`, which iOS reads only on the main actor (so the app delegate reads it first) and returns as just `iPhone` unless the app has the `com.apple.developer.device-information.user-assigned-device-name` entitlement. Apple grants that entitlement on request (developer.apple.com/contact/request/user-assigned-device-name); it then has to be enabled on the App ID and added to `mac/phone/byre.entitlements`. The simulator returns the simulator device's own name without it.
 - SwiftTerm's iOS `TerminalViewDelegate` requires `requestOpenLink`, which its macOS one provides a default for.

mac/Sources/Byre/Tailnet.swift

@@ -26,7 +26,11 @@ func slug(_ text: String) -> String {
 
 final class TailnetNode: Sendable {
     let sd: tailscale
+    #if os(macOS)
     let hostname = "byre-app-\(slug(deviceName))"
+    #else
+    let hostname = "byre-app-\(slug(deviceKind))"
+    #endif
     private let socks = TailnetProxy()
 
     init() {