feat: unified shell, diagnostics pack, native Office, sticky board

Make Surface remote debugging and classroom workflows viable: always-on
structured logs with one-click zip export, a single AppShell chrome,
OOXML PPTX/DOCX annotation without LibreOffice, and a first-class sticky
board. Also drop spike/legacy ink widgets and tighten pen feel
(predictor, PenInfoHistory, page-tile layer).

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/editor/canvas/input_diagnostics.dart

@@ -8,6 +8,7 @@
 
 import 'package:flutter/foundation.dart';
 
+import '../../diagnostics/frame_sampler.dart';
 import '../input/diagnostic_logger.dart';
 
 class InputDiagnostics extends ChangeNotifier {
@@ -62,6 +63,12 @@ class InputDiagnostics extends ChangeNotifier {
         '${scaleDrop ? " SDROP" : ""}${focalDrop ? " FDROP" : ""}';
     _trace.add(line);
     if (_trace.length > 24) _trace.removeAt(0);
+    FrameSampler.instance.recordZoom(
+      rawScale: rawScale,
+      scaleDrop: scaleDrop,
+      focalDrop: focalDrop,
+      focalJumpPx: focalJumpPx,
+    );
     DiagnosticLogger.instance.log('ZOOM $line');
     notifyListeners();
   }