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/input/pen_input_service.dart

@@ -23,6 +23,8 @@ import 'dart:async';
 
 import 'package:flutter/services.dart';
 
+import '../../diagnostics/badnote_log.dart';
+import '../../diagnostics/pen_event_ring.dart';
 import 'diagnostic_logger.dart';
 
 /// Latest hardware pen state delivered by the native observer.
@@ -169,6 +171,29 @@ class PenInputService {
     final key = '$rawPtr,$rawPen,$rawMask,$btnChange,${_current.tiltX},${_current.tiltY}';
     if (key != _lastPenLogKey) {
       _lastPenLogKey = key;
+      PenEventRing.instance.recordHardware(
+        barrel: _current.barrel,
+        eraser: _current.eraser,
+        inverted: _current.inverted,
+        tiltX: _current.tiltX,
+        tiltY: _current.tiltY,
+      );
+      BadNoteLog.instance.debug(
+        LogSubsystem.penNative,
+        'pen_hw',
+        fields: {
+          'ptrFlags': '0x${rawPtr.toRadixString(16)}',
+          'penFlags': '0x${rawPen.toRadixString(16)}',
+          'mask': '0x${rawMask.toRadixString(16)}',
+          'btnChg': btnChange,
+          'tiltX': _current.tiltX,
+          'tiltY': _current.tiltY,
+          'resolved': '0x${flags.toRadixString(16)}',
+          'barrel': _current.barrel,
+          'eraser': _current.eraser,
+          'inverted': _current.inverted,
+        },
+      );
       DiagnosticLogger.instance.log(
         'PEN ptrFlags=0x${rawPtr.toRadixString(16)} '
         'penFlags=0x${rawPen.toRadixString(16)} '