feat: OneNote-style notebooks, text fonts, and page navigation

Add notebook.json containers with multi-member pages, fix PDF text
editing (size/bold/drag/double-tap), index SidecarText in search, and
share keyboard page shortcuts plus a PDF scrubber.

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

lib/services/vault_search_index.dart

@@ -166,8 +166,13 @@ class VaultSearchIndex {
   }) {
     final parts = <String>[title];
     if (sidecar != null) {
-      // Typed text boxes: a stroke carries `textContent` regardless of tool
-      // (EditorTool has only pen/highlighter/eraser; text is a content flag).
+      // Typed text boxes on the pen-first text tool (SidecarText), plus any
+      // legacy stroke-embedded textContent.
+      for (final pageTexts in sidecar.texts.values) {
+        for (final t in pageTexts) {
+          if (t.text.trim().isNotEmpty) parts.add(t.text.trim());
+        }
+      }
       for (final pageStrokes in sidecar.strokes.values) {
         for (final stroke in pageStrokes) {
           final text = stroke.textContent;