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/bloc/editor_bloc.dart

@@ -107,6 +107,12 @@ class ToolChanged extends EditorEvent {
   ToolChanged(this.tool);
 }
 
+/// 再次点击已激活的工具 — 重新弹出设置面板
+class ToolReactivated extends EditorEvent {
+  final EditorTool tool;
+  ToolReactivated(this.tool);
+}
+
 /// 加载已有元素
 class ElementsLoaded extends EditorEvent {
   final List<JournalElement> elements;
@@ -227,6 +233,9 @@ class EditorState {
   final bool isDirty;
   final DateTime? lastSavedAt;
 
+  // 工具重新激活时间戳（用于驱动面板重新弹出）
+  final int toolReactivatedAt;
+
   const EditorState({
     this.strokes = const [],
     this.redoStack = const [],
@@ -243,6 +252,7 @@ class EditorState {
     this.title = '',
     this.isDirty = false,
     this.lastSavedAt,
+    this.toolReactivatedAt = 0,
   });
 
   EditorState copyWith({
@@ -261,6 +271,7 @@ class EditorState {
     String? title,
     bool? isDirty,
     DateTime? lastSavedAt,
+    int? toolReactivatedAt,
   }) =>
       EditorState(
         strokes: strokes ?? this.strokes,
@@ -279,6 +290,7 @@ class EditorState {
         title: title ?? this.title,
         isDirty: isDirty ?? this.isDirty,
         lastSavedAt: lastSavedAt ?? this.lastSavedAt,
+        toolReactivatedAt: toolReactivatedAt ?? this.toolReactivatedAt,
       );
 
   /// 是否处于手写模式
@@ -330,6 +342,7 @@ class EditorBloc extends Bloc<EditorEvent, EditorState> {
 
     // 工具栏事件
     on<ToolChanged>(_onToolChanged);
+    on<ToolReactivated>(_onToolReactivated);
 
     // 标签/心情/标题事件
     on<TagAdded>(_onTagAdded);
@@ -514,6 +527,13 @@ class EditorBloc extends Bloc<EditorEvent, EditorState> {
     ));
   }
 
+  void _onToolReactivated(ToolReactivated event, Emitter<EditorState> emit) {
+    // 不改变 activeTool，仅递增时间戳驱动 UI 层重新弹出面板
+    emit(state.copyWith(
+      toolReactivatedAt: DateTime.now().millisecondsSinceEpoch,
+    ));
+  }
+
   // ============================================================
   // 标签/心情/标题事件处理
   // ============================================================