fix(studio): daemon-start probes health first + shows a readable error

'Tap to start' on an already-running hub reported 'daemon could not be
started' (the start failed because it was already up) then flashed the
error away as a SnackBar — confusing next to the sidebar's 'connected'.
Now: on a failed start, probe the hub; if it answers, just connect (no
false error). If it is genuinely down, show the daemon's stderr in a
persistent, copyable dialog (showFaiProcessErrorDialog) instead of a
SnackBar that vanishes before the operator can read or copy it.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/data/error_presentation.dart

@@ -109,6 +109,27 @@ void showFaiProcessError(
   );
 }
 
+/// Like [showFaiProcessError] but as a persistent modal dialog. Use for
+/// failures the operator needs time to read and copy (a daemon that
+/// won't start) — a SnackBar flashes away before they can act on it.
+Future<void> showFaiProcessErrorDialog(
+  BuildContext context,
+  String source,
+  String stdout,
+  String stderr, {
+  String? title,
+}) {
+  final detail = [stderr.trim(), stdout.trim()]
+      .where((s) => s.isNotEmpty)
+      .join('\n\n');
+  return showFaiErrorDialog(
+    context,
+    source,
+    detail.isEmpty ? 'process exited non-zero (no output)' : detail,
+    title: title,
+  );
+}
+
 /// Show [error] as a centered modal dialog. Use this when the
 /// failure blocks meaningful interaction (auth missing, hub
 /// unreachable) — a SnackBar would be too easy to dismiss.