fix(app): 修复 4 个 Flutter 交互问题

1. 首页数据不刷新 — JournalRepository 添加 onJournalChanged
   Stream 变更通知，HomeBloc 订阅后自动刷新
2. 画笔再次点击不弹出面板 — 添加 ToolReactivated 事件，
   工具栏检测已激活工具时发出重新激活信号
3. 钢笔铅笔效果一样 — 调整 perfect_freehand 参数
   (pen: size 10/smooth 0.65, pencil: size 3/smooth 0.35)
4. 橡皮擦不生效 — ActiveStrokePainter 橡皮擦模式绘制
   半透明灰色反馈，笔画完成后 setState 触发 Layer 1 重绘
5. 贴纸文字无法缩放 — DraggableElement 用 Scale 手势
   替换 Pan 手势，支持双指缩放和旋转

app/lib/features/editor/widgets/draggable_element.dart

@@ -19,6 +19,8 @@ class DraggableElement extends StatefulWidget {
   final bool isSelected;
   final ValueChanged<String> onTap;
   final void Function(String id, double x, double y) onMoved;
+  final void Function(String id, double w, double h)? onResized;
+  final void Function(String id, double rotation)? onRotated;
   final ValueChanged<String> onDeleted;
 
   const DraggableElement({
@@ -27,6 +29,8 @@ class DraggableElement extends StatefulWidget {
     this.isSelected = false,
     required this.onTap,
     required this.onMoved,
+    this.onResized,
+    this.onRotated,
     required this.onDeleted,
   });
 
@@ -41,6 +45,11 @@ class _DraggableElementState extends State<DraggableElement> {
   late double _height;
   late double _rotation;
 
+  // Scale 手势状态
+  double _baseWidth = 0;
+  double _baseHeight = 0;
+  double _baseRotation = 0;
+
   @override
   void initState() {
     super.initState();
@@ -76,15 +85,35 @@ class _DraggableElementState extends State<DraggableElement> {
       child: Transform.rotate(
         angle: _rotation,
         child: GestureDetector(
-          // 拖拽移动
-          onPanUpdate: (details) {
+          // 缩放开始 — 记录基准值
+          onScaleStart: (details) {
+            _baseWidth = _width;
+            _baseHeight = _height;
+            _baseRotation = _rotation;
+          },
+          // 缩放更新 — 支持单指拖拽 + 双指缩放/旋转
+          onScaleUpdate: (details) {
             setState(() {
-              _x += details.delta.dx;
-              _y += details.delta.dy;
+              // 拖拽（单指和双指都支持）
+              _x += details.focalPointDelta.dx;
+              _y += details.focalPointDelta.dy;
+
+              // 双指缩放 + 旋转
+              if (details.pointerCount >= 2) {
+                final newW = (_baseWidth * details.scale).clamp(40.0, 400.0);
+                final newH = (_baseHeight * details.scale).clamp(40.0, 400.0);
+                _width = newW;
+                _height = newH;
+                _rotation = _baseRotation + details.rotation;
+              }
             });
             widget.onMoved(widget.element.id, _x, _y);
+            if (details.pointerCount >= 2) {
+              widget.onResized?.call(widget.element.id, _width, _height);
+              widget.onRotated?.call(widget.element.id, _rotation);
+            }
           },
-          onPanEnd: (_) {
+          onScaleEnd: (_) {
             // 确保最终位置已通知
             widget.onMoved(widget.element.id, _x, _y);
           },