Refine school script diagnostics and document-state capture

mobile/lib/services/diagnostic_log.dart

@@ -3,6 +3,8 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
+import '../app/app_version.dart';
+
 /// Small, structured breadcrumbs. Never accepts raw URLs, HTML or exceptions.
 class DiagnosticLog {
   DiagnosticLog({DateTime Function()? clock}) : clock = clock ?? DateTime.now;
@@ -183,7 +185,9 @@ class DiagnosticLog {
     _trim();
     await flush();
     final header =
-        'TPSchedule diagnostic log\nWindow: last 10 minutes (UTC timestamps)\n'
+        'TPSchedule diagnostic log\nApp: TPSchedule $appVersion+$appBuildNumber\n'
+        'Exported at: ${clock().toUtc().toIso8601String()}\n'
+        'Window: last 10 minutes (UTC timestamps)\n'
         'Up to 500 recent events; no passwords, cookies, HTML or feedback text.\n';
     return Uint8List.fromList(
       utf8.encode('$header${_entries.map(jsonEncode).join('\n')}\n'),