fix: PDF finger ink, chrome UX, OneNote pens, and pen physics

Wire finger drawing on PDF without breaking pinch; auto-hide page scrubber and fix bounce; share sticky tools with resize and per-page remember; side-button select; separate pen slots with colors; rnote pressure shapes plus tip-velocity width and lower stroke latency.

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

lib/editor/canvas/pen_interactive_viewer.dart

@@ -53,7 +53,7 @@ const double _kScaleGlitchHi = 1.18;
 /// During a 2-finger gesture the focal point (finger midpoint) should move
 /// smoothly. A single-frame local jump beyond this is a Windows touch misread,
 /// and the frame is dropped (position-jump guard).
-const double _kFocalGlitchPx = 100.0;
+const double _kFocalGlitchPx = 64.0;
 
 const double _kDrag = 0.0000135;
 
@@ -376,26 +376,9 @@ class _PenInteractiveViewerState extends State<PenInteractiveViewer>
         _animation!.addListener(_handleInertiaAnimation);
         _controller.forward();
       case _GestureType.scale:
-        if (details.scaleVelocity.abs() < 0.1) return;
-        final double scale = _transformer.value.getMaxScaleOnAxis();
-        final FrictionSimulation frictionSimulation = FrictionSimulation(
-          widget.interactionEndFrictionCoefficient * widget.scaleFactor,
-          scale,
-          details.scaleVelocity / 10,
-        );
-        final double tFinal = _getFinalTime(
-          details.scaleVelocity.abs(),
-          widget.interactionEndFrictionCoefficient,
-          effectivelyMotionless: 0.1,
-        );
-        _scaleAnimation = Tween<double>(
-          begin: scale,
-          end: frictionSimulation.x(tFinal),
-        ).animate(
-            CurvedAnimation(parent: _scaleController, curve: Curves.decelerate));
-        _scaleController.duration = Duration(milliseconds: (tFinal * 1000).round());
-        _scaleAnimation!.addListener(_handleScaleAnimation);
-        _scaleController.forward();
+        // No scale fling: Windows touch often reports noisy scaleVelocity that
+        // animates past the intended zoom and feels like a "jump" after pinch.
+        return;
       case null:
         break;
     }