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/services/office/office_document.dart

@@ -0,0 +1,98 @@
+/// Shared OOXML document models for native Word/PPT parsing.
+library;
+
+class OfficeTextRun {
+  const OfficeTextRun({
+    required this.text,
+    this.x = 0,
+    this.y = 0,
+    this.width = 0,
+    this.height = 0,
+    this.fontSize = 18,
+  });
+
+  final String text;
+  final double x;
+  final double y;
+  final double width;
+  final double height;
+  final double fontSize;
+}
+
+class OfficeImage {
+  const OfficeImage({
+    required this.bytesPath,
+    this.x = 0,
+    this.y = 0,
+    this.width = 0,
+    this.height = 0,
+  });
+
+  final String bytesPath;
+  final double x;
+  final double y;
+  final double width;
+  final double height;
+}
+
+class OfficeSlide {
+  const OfficeSlide({
+    required this.index,
+    required this.width,
+    required this.height,
+    this.runs = const [],
+    this.images = const [],
+    this.plainText = '',
+  });
+
+  final int index;
+  final double width;
+  final double height;
+  final List<OfficeTextRun> runs;
+  final List<OfficeImage> images;
+  final String plainText;
+}
+
+class ParsedPptx {
+  const ParsedPptx({
+    required this.sourcePath,
+    required this.slides,
+  });
+
+  final String sourcePath;
+  final List<OfficeSlide> slides;
+
+  String get allText =>
+      slides.map((s) => '--- Slide ${s.index + 1} ---\n${s.plainText}').join('\n\n');
+
+  /// Alias used by [PptxService.extractText].
+  String get plainText => allText;
+}
+
+enum DocBlockType { heading, paragraph, tableRow, image }
+
+class DocBlock {
+  const DocBlock({
+    required this.type,
+    required this.text,
+    this.level = 0,
+    this.imagePath,
+  });
+
+  final DocBlockType type;
+  final String text;
+  final int level;
+  final String? imagePath;
+}
+
+class ParsedDocx {
+  const ParsedDocx({
+    required this.sourcePath,
+    required this.blocks,
+  });
+
+  final String sourcePath;
+  final List<DocBlock> blocks;
+
+  String get plainText => blocks.map((b) => b.text).where((t) => t.isNotEmpty).join('\n');
+}