Read the iPhone's own name for its host and tailnet node

TODO.md

@@ -1,4 +1,6 @@
 # Bugs
+- Enable the iPhone device-name entitlement
+  Once Apple grants User Assigned Device Name to the App ID `run.fc.byre.ios` (Certificates, Identifiers & Profiles, Capability Requests), turn it on there and add `com.apple.developer.device-information.user-assigned-device-name` to `mac/phone/byre.entitlements`. Until then `UIDevice.current.name` returns `iPhone` on a real phone. Check on a TestFlight build that the Status tab lists the phone by its own name.
 
 # M1 — One agent end to end
 

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.
-- `ProcessInfo.hostName` is the Mac's name in the simulator and meaningless on a phone, so the phone's tailnet node and `Byre-Host` are named `iPhone`.
+- 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.
 - SwiftTerm's iOS `TerminalViewDelegate` requires `requestOpenLink`, which its macOS one provides a default for.

mac/Sources/Byre/API.swift

@@ -4,6 +4,9 @@ import HTTPTypes
 import OpenAPIRuntime
 import OpenAPIURLSession
 import os
+#if os(iOS)
+import UIKit
+#endif
 
 let log = Logger(subsystem: "run.fc.byre.mac", category: "byre")
 
@@ -104,7 +107,7 @@ private let clientID = newID("cli")
 #if os(macOS)
 let deviceName = Host.current().localizedName ?? ProcessInfo.processInfo.hostName
 #else
-let deviceName = deviceKind
+let deviceName = MainActor.assumeIsolated { UIDevice.current.name }
 #endif
 
 final class API: Sendable {

mac/Sources/Byre/Phone.swift

@@ -3,6 +3,8 @@ import SwiftUI
 
 final class PhoneDelegate: NSObject, UIApplicationDelegate {
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool {
+        // deviceName reads UIDevice, which is main-actor only, so it must first be read here.
+        _ = deviceName
         Notifier.shared.install()
         UITextView.appearance().textContainerInset = .zero
         return true