Fix the iPhone review's findings

- Cancelling (Change headset, Forget) invalidates the attempt in flight; a
  connection only becomes the app's once every step finished for it.
- A server that stops while the tunnel opens is noticed (exit callbacks are
  synchronised and replayed), and the app isn't left showing a dead page.
- The port is read only once the digits are complete, and range-checked.
- Other versions in ~/.cache/frame-control stay unless untouched for 14 days,
  so a second phone or iPad isn't cut off.
- The key is appended on its own line even if authorized_keys lacks a final
  newline.
- The app checks every 20 s, and on returning to the foreground, that the SSH
  session still answers, and reconnects if not.
- The ssh stand-in runs the command as its own process group and passes a
  TERM on to all of it, so a live-video ffmpeg stops with its stream.
- Touch screens show the library's Play buttons (the rule now follows the
  base one); the failure screen only says it's retrying when it is; the page
  says the app reconnects rather than naming a desktop menu.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

ios/FrameControl/Views/RootView.swift

@@ -12,7 +12,7 @@ struct RootView: View {
             case .connecting(let step):
                 ConnectingView(step: step, host: model.settings?.host) { model.showSetup() }
             case .failed(let message):
-                FailedView(message: message, canRetry: model.settings != nil,
+                FailedView(message: message, canRetry: model.settings != nil, retrying: model.retrying,
                            retry: { Task { await model.connect() } }, change: { model.showSetup() })
             case .ready(let url):
                 WebShell(url: url, model: model).ignoresSafeArea()
@@ -50,6 +50,7 @@ struct ConnectingView: View {
 struct FailedView: View {
     let message: String
     let canRetry: Bool
+    let retrying: Bool
     let retry: () -> Void
     let change: () -> Void
 
@@ -58,7 +59,7 @@ struct FailedView: View {
             Image(systemName: "wifi.exclamationmark").font(.system(size: 44)).foregroundStyle(.orange)
             Text("Can't reach the Frame").font(.title3.bold())
             Text(message).multilineTextAlignment(.center).foregroundStyle(Color.frameMuted)
-            if canRetry { Text("Trying again every few seconds.").font(.footnote).foregroundStyle(Color.frameMuted) }
+            if retrying { Text("Trying again every few seconds.").font(.footnote).foregroundStyle(Color.frameMuted) }
             if canRetry {
                 Button("Try again", action: retry).buttonStyle(.borderedProminent).controlSize(.large)
             }