fix: restore PDF pen capture and overhaul sticky/pens/pages

Reinstall PenCaptureBinding so stylus ink hits again; keep finger Listener translucent under pinch; page-anchor sticky with drag/resize; OneNote pen slots (brush+width+color); blank-note multi-page; default side button to hold-select-text.

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

lib/editor/canvas/pen_palette_widgets.dart

@@ -8,6 +8,7 @@ import 'package:flutter/material.dart';
 
 import '../../l10n/app_localizations.dart';
 import '../engine/brush.dart';
+import '../input/pen_slots.dart';
 import 'editor_tool.dart';
 
 /// Shared ink color palette for PDF / note / slide / scratch editors.
@@ -87,8 +88,8 @@ IconData shapeIcon(ShapeKind kind) => switch (kind) {
       ShapeKind.arrow => Icons.arrow_outward,
     };
 
-/// OneNote-style pen slot: each brush is its own toolbar button with a color
-/// underline (per-brush remembered color). Prefer this over [BrushPickerButton]
+/// OneNote-style pen slot: each slot is its own toolbar button with a color
+/// underline (slot-remembered color). Prefer this over [BrushPickerButton]
 /// when the UX wants pens visible side-by-side.
 class PenSlotButton extends StatelessWidget {
   const PenSlotButton({
@@ -98,6 +99,7 @@ class PenSlotButton extends StatelessWidget {
     required this.color,
     required this.tooltip,
     required this.onPressed,
+    this.widthHint,
   });
 
   final BrushKind kind;
@@ -106,11 +108,18 @@ class PenSlotButton extends StatelessWidget {
   final String tooltip;
   final VoidCallback onPressed;
 
+  /// Optional page-width fraction; when set, underline height scales slightly
+  /// so thicker slots read visually thicker. Null keeps the fixed 3px bar.
+  final double? widthHint;
+
   @override
   Widget build(BuildContext context) {
     final cs = Theme.of(context).colorScheme;
     final iconColor =
         selected ? cs.onSecondaryContainer : cs.onSurfaceVariant;
+    final barHeight = widthHint == null
+        ? 3.0
+        : (2.0 + (widthHint! / kThicknessLarge).clamp(0.0, 1.0) * 3.0);
     return Tooltip(
       message: tooltip,
       child: InkWell(
@@ -131,7 +140,7 @@ class PenSlotButton extends StatelessWidget {
               const SizedBox(height: 3),
               Container(
                 width: 16,
-                height: 3,
+                height: barHeight,
                 decoration: BoxDecoration(
                   color: color,
                   borderRadius: BorderRadius.circular(2),
@@ -145,6 +154,119 @@ class PenSlotButton extends StatelessWidget {
   }
 }
 
+/// Compact thickness control: S / M / L presets + a custom slider. Writes the
+/// chosen page-width fraction via [onChanged] (typically
+/// [PenSlotsController.setActiveWidth]).
+class ThicknessPickerButton extends StatelessWidget {
+  const ThicknessPickerButton({
+    super.key,
+    required this.width,
+    required this.onChanged,
+    this.tooltip = 'Thickness',
+  });
+
+  /// Current stroke width (page-width fraction).
+  final double width;
+
+  final ValueChanged<double> onChanged;
+  final String tooltip;
+
+  static String _labelFor(double w) {
+    if ((w - kThicknessSmall).abs() < 0.0003) return 'S';
+    if ((w - kThicknessMedium).abs() < 0.0003) return 'M';
+    if ((w - kThicknessLarge).abs() < 0.0003) return 'L';
+    return '·';
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final cs = Theme.of(context).colorScheme;
+    return PopupMenuButton<double>(
+      tooltip: tooltip,
+      onSelected: onChanged,
+      itemBuilder: (context) => [
+        PopupMenuItem<double>(
+          value: kThicknessSmall,
+          child: Row(
+            children: [
+              const Text('S'),
+              const Spacer(),
+              if ((width - kThicknessSmall).abs() < 0.0003)
+                Icon(Icons.check, size: 18, color: cs.primary),
+            ],
+          ),
+        ),
+        PopupMenuItem<double>(
+          value: kThicknessMedium,
+          child: Row(
+            children: [
+              const Text('M'),
+              const Spacer(),
+              if ((width - kThicknessMedium).abs() < 0.0003)
+                Icon(Icons.check, size: 18, color: cs.primary),
+            ],
+          ),
+        ),
+        PopupMenuItem<double>(
+          value: kThicknessLarge,
+          child: Row(
+            children: [
+              const Text('L'),
+              const Spacer(),
+              if ((width - kThicknessLarge).abs() < 0.0003)
+                Icon(Icons.check, size: 18, color: cs.primary),
+            ],
+          ),
+        ),
+        PopupMenuItem<double>(
+          enabled: false,
+          child: SizedBox(
+            width: 180,
+            child: StatefulBuilder(
+              builder: (context, setLocal) {
+                final v = width.clamp(kPenSlotWidthMin, kPenSlotWidthMax);
+                return Slider(
+                  value: v,
+                  min: kPenSlotWidthMin,
+                  max: kPenSlotWidthMax,
+                  onChanged: (next) {
+                    onChanged(next);
+                    setLocal(() {});
+                  },
+                );
+              },
+            ),
+          ),
+        ),
+      ],
+      child: AnimatedContainer(
+        duration: const Duration(milliseconds: 150),
+        margin: const EdgeInsets.symmetric(horizontal: 2),
+        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
+        decoration: BoxDecoration(
+          color: Colors.transparent,
+          borderRadius: BorderRadius.circular(20),
+        ),
+        child: Row(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(Icons.line_weight, size: 20, color: cs.onSurfaceVariant),
+            const SizedBox(width: 2),
+            Text(
+              _labelFor(width),
+              style: TextStyle(
+                fontSize: 12,
+                fontWeight: FontWeight.w600,
+                color: cs.onSurfaceVariant,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
 /// A dropdown that selects the active PEN brush (fountain / ballpoint / pencil).
 ///
 /// Highlighter and eraser remain separate tools. Tapping the button opens a