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/diagnostics/diagnostic_chrome.dart

@@ -0,0 +1,174 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+
+import 'badnote_log.dart';
+import 'diagnostic_export.dart';
+import '../editor/canvas/input_diagnostics.dart';
+import '../editor/input/diagnostic_logger.dart';
+import '../editor/input/pen_input_service.dart';
+
+/// Shared diagnostics chrome: overlay readout + export action.
+/// Mount on any document surface (note / PDF / PPT / board).
+class DiagnosticChrome extends StatefulWidget {
+  const DiagnosticChrome({
+    super.key,
+    required this.child,
+    this.initiallyVisible = false,
+  });
+
+  final Widget child;
+  final bool initiallyVisible;
+
+  @override
+  State<DiagnosticChrome> createState() => DiagnosticChromeState();
+}
+
+class DiagnosticChromeState extends State<DiagnosticChrome> {
+  late bool _visible = widget.initiallyVisible;
+  bool _exporting = false;
+  String? _lastExportPath;
+
+  bool get isVisible => _visible;
+
+  void toggle() {
+    setState(() {
+      _visible = !_visible;
+      if (_visible) {
+        DiagnosticLogger.instance.start();
+        InputDiagnostics.instance.reset();
+      } else {
+        DiagnosticLogger.instance.stop();
+      }
+    });
+  }
+
+  Future<void> exportPack() async {
+    if (_exporting) return;
+    setState(() => _exporting = true);
+    try {
+      final result = await DiagnosticExport.instance.exportPack();
+      if (!mounted) return;
+      setState(() => _lastExportPath = result.zipPath);
+      await Clipboard.setData(ClipboardData(text: result.zipPath));
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(
+            '诊断包已导出 (${result.bytes} bytes)\n路径已复制到剪贴板',
+          ),
+          duration: const Duration(seconds: 5),
+        ),
+      );
+    } catch (e) {
+      BadNoteLog.instance.error(LogSubsystem.diag, 'export_failed', fields: {
+        'error': '$e',
+      });
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('导出失败: $e')),
+      );
+    } finally {
+      if (mounted) setState(() => _exporting = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      fit: StackFit.expand,
+      children: [
+        widget.child,
+        if (_visible)
+          Positioned(
+            left: 8,
+            right: 8,
+            bottom: 8,
+            child: Material(
+              elevation: 6,
+              borderRadius: BorderRadius.circular(8),
+              color: Colors.black.withValues(alpha: 0.82),
+              child: Padding(
+                padding: const EdgeInsets.all(10),
+                child: DefaultTextStyle(
+                  style: const TextStyle(
+                    color: Colors.white,
+                    fontSize: 11,
+                    fontFamily: 'monospace',
+                    height: 1.35,
+                  ),
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      ListenableBuilder(
+                        listenable: InputDiagnostics.instance,
+                        builder: (context, _) {
+                          return Text(
+                            '${InputDiagnostics.instance.summary()}\n'
+                            '${PenInputService.instance.debugSummary}\n'
+                            'log: ${BadNoteLog.instance.path ?? "(starting…)"}\n'
+                            'session: ${BadNoteLog.instance.sessionId}'
+                            '${_lastExportPath != null ? "\nlast zip: $_lastExportPath" : ""}',
+                          );
+                        },
+                      ),
+                      const SizedBox(height: 8),
+                      Row(
+                        children: [
+                          TextButton(
+                            onPressed: () => InputDiagnostics.instance.reset(),
+                            child: const Text('Reset',
+                                style: TextStyle(color: Colors.white70)),
+                          ),
+                          TextButton(
+                            onPressed: _exporting ? null : exportPack,
+                            child: Text(
+                              _exporting ? 'Exporting…' : 'Export pack',
+                              style: const TextStyle(color: Colors.lightGreenAccent),
+                            ),
+                          ),
+                          TextButton(
+                            onPressed: toggle,
+                            child: const Text('Hide',
+                                style: TextStyle(color: Colors.white54)),
+                          ),
+                        ],
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+            ),
+          ),
+      ],
+    );
+  }
+}
+
+/// Compact icon button for app bars / toolbars.
+class DiagnosticToggleButton extends StatelessWidget {
+  const DiagnosticToggleButton({
+    super.key,
+    required this.onToggle,
+    required this.onExport,
+  });
+
+  final VoidCallback onToggle;
+  final VoidCallback onExport;
+
+  @override
+  Widget build(BuildContext context) {
+    return PopupMenuButton<String>(
+      tooltip: 'Diagnostics',
+      icon: const Icon(Icons.bug_report_outlined),
+      onSelected: (v) {
+        if (v == 'toggle') onToggle();
+        if (v == 'export') onExport();
+      },
+      itemBuilder: (context) => const [
+        PopupMenuItem(value: 'toggle', child: Text('Toggle overlay')),
+        PopupMenuItem(value: 'export', child: Text('Export diagnostic pack')),
+      ],
+    );
+  }
+}