feat(app): 添加 EditorBloc.LoadJournal event — 加载已有日记数据

- LoadJournal event: 原子加载 title/mood/tags/strokes/elements/lastSavedAt
- _onLoadJournal handler: 不触发 auto-save (isDirty=false)
- 单元测试: 验证 LoadJournal 正确还原所有状态字段
- mood_bloc: linter 补充 foundation.dart import

app/lib/features/editor/bloc/editor_bloc.dart

@@ -163,6 +163,28 @@ class TextFormatChanged extends EditorEvent {
   });
 }
 
+/// 加载已有日记数据（从 JournalRepository 读取后原子注入）
+///
+/// 与 StrokesLoaded/ElementsLoaded/TagsLoaded 等细粒度事件不同，
+/// LoadJournal 一次性还原所有日记状态，不触发 auto-save (isDirty=false)。
+class LoadJournal extends EditorEvent {
+  final String title;
+  final Mood mood;
+  final List<String> tags;
+  final List<Stroke> strokes;
+  final List<JournalElement> elements;
+  final DateTime? lastSavedAt;
+
+  LoadJournal({
+    required this.title,
+    required this.mood,
+    required this.tags,
+    required this.strokes,
+    required this.elements,
+    this.lastSavedAt,
+  });
+}
+
 // ============================================================
 // 状态
 // ============================================================
@@ -303,6 +325,9 @@ class EditorBloc extends Bloc<EditorEvent, EditorState> {
     on<ElementSelected>(_onElementSelected);
     on<ElementsLoaded>(_onElementsLoaded);
 
+    // 日记加载事件
+    on<LoadJournal>(_onLoadJournal);
+
     // 工具栏事件
     on<ToolChanged>(_onToolChanged);
 
@@ -458,6 +483,25 @@ class EditorBloc extends Bloc<EditorEvent, EditorState> {
     emit(state.copyWith(elements: event.elements));
   }
 
+  // ============================================================
+  // 日记加载事件处理
+  // ============================================================
+
+  /// 加载已有日记 — 原子操作，一次性还原所有状态
+  ///
+  /// 不触发 auto-save（isDirty=false），因为这是加载而非用户编辑。
+  void _onLoadJournal(LoadJournal event, Emitter<EditorState> emit) {
+    emit(state.copyWith(
+      title: event.title,
+      selectedMood: event.mood,
+      tags: event.tags,
+      strokes: event.strokes,
+      elements: event.elements,
+      lastSavedAt: event.lastSavedAt,
+      isDirty: false,
+    ));
+  }
+
   // ============================================================
   // 工具栏事件处理
   // ============================================================

app/lib/features/mood/bloc/mood_bloc.dart

@@ -1,5 +1,6 @@
 // 心情 BLoC — 通过 API 加载心情统计数据
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:nuanji_app/data/models/journal_entry.dart';
 import 'package:nuanji_app/data/remote/api_client.dart';

app/test/features/editor/bloc/editor_bloc_test.dart

@@ -6,6 +6,7 @@
 import 'dart:math';
 
 import 'package:flutter_test/flutter_test.dart';
+import 'package:nuanji_app/data/models/journal_entry.dart';
 import 'package:nuanji_app/data/models/journal_element.dart';
 import 'package:nuanji_app/features/editor/bloc/editor_bloc.dart';
 import 'package:nuanji_app/features/editor/widgets/stroke_model.dart';
@@ -262,5 +263,35 @@ void main() {
 
       bloc.close();
     });
+
+    // ===== LoadJournal 原子加载 =====
+
+    test('LoadJournal 还原已有日记数据', () async {
+      final strokes = [_testStroke(id: 's1')];
+      final elements = [
+        JournalElement.createSticker(
+          journalId: 'j1',
+          emoji: '😊',
+          position: Offset.zero,
+        ),
+      ];
+
+      final state = await dispatch(LoadJournal(
+        title: '测试日记',
+        mood: Mood.happy,
+        tags: const ['开心', '学校'],
+        strokes: strokes,
+        elements: elements,
+        lastSavedAt: DateTime(2026, 6, 1),
+      ));
+
+      expect(state.title, '测试日记');
+      expect(state.selectedMood, Mood.happy);
+      expect(state.tags, ['开心', '学校']);
+      expect(state.strokes.length, 1);
+      expect(state.elements.length, 1);
+      expect(state.lastSavedAt, DateTime(2026, 6, 1));
+      expect(state.isDirty, isFalse, reason: 'LoadJournal 不应标记为 dirty');
+    });
   });
 }