feat(app): 编辑器完成按钮接入分享面板 — ShareBottomSheet + sharedToClass更新

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

@@ -0,0 +1,119 @@
+// 分享 BottomSheet — 编辑器完成后选择分享到班级或仅自己可见
+//
+// 设计要点：
+// - 温暖友好的文案（面向小学生）
+// - 分享到班级（有班级时显示）/ 仅自己可见
+// - 无班级时提示加入班级后可分享
+
+import 'package:flutter/material.dart';
+
+/// 编辑器完成后的分享选择面板
+class ShareBottomSheet extends StatelessWidget {
+  final String? classId;
+  final String className;
+  final void Function(bool shareToClass) onDecision;
+
+  const ShareBottomSheet({
+    super.key,
+    required this.classId,
+    required this.className,
+    required this.onDecision,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final hasClass = classId != null && classId.isNotEmpty;
+    final theme = Theme.of(context);
+
+    return Container(
+      padding: const EdgeInsets.all(20),
+      decoration: BoxDecoration(
+        color: theme.colorScheme.surface,
+        borderRadius: const BorderRadius.vertical(top: Radius.circular(22)),
+      ),
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          // 拖拽条
+          Center(
+            child: Container(
+              margin: const EdgeInsets.only(bottom: 16),
+              width: 40,
+              height: 4,
+              decoration: BoxDecoration(
+                color: Colors.grey.shade300,
+                borderRadius: BorderRadius.circular(2),
+              ),
+            ),
+          ),
+          Text(
+            '日记写好了！',
+            style: theme.textTheme.titleMedium,
+          ),
+          const SizedBox(height: 8),
+          Text(
+            '要分享给老师和同学们看看吗？',
+            style: theme.textTheme.bodyMedium?.copyWith(
+              color: Colors.grey.shade600,
+            ),
+          ),
+          const SizedBox(height: 24),
+
+          // 分享到班级
+          if (hasClass) ...[
+            SizedBox(
+              width: double.infinity,
+              height: 52,
+              child: FilledButton.icon(
+                onPressed: () {
+                  onDecision(true);
+                  Navigator.pop(context);
+                },
+                icon: const Icon(Icons.group),
+                label: Text('分享到 $className'),
+                style: FilledButton.styleFrom(
+                  shape: RoundedRectangleBorder(
+                    borderRadius: BorderRadius.circular(12),
+                  ),
+                ),
+              ),
+            ),
+            const SizedBox(height: 12),
+          ],
+
+          // 仅自己可见
+          SizedBox(
+            width: double.infinity,
+            height: 52,
+            child: OutlinedButton.icon(
+              onPressed: () {
+                onDecision(false);
+                Navigator.pop(context);
+              },
+              icon: const Icon(Icons.lock_outline),
+              label: const Text('仅自己可见'),
+              style: OutlinedButton.styleFrom(
+                shape: RoundedRectangleBorder(
+                  borderRadius: BorderRadius.circular(12),
+                ),
+              ),
+            ),
+          ),
+
+          // 无班级时的提示
+          if (!hasClass) ...[
+            const SizedBox(height: 12),
+            Text(
+              '加入班级后可以分享给老师和同学哦',
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: Colors.grey.shade500,
+              ),
+            ),
+          ],
+
+          const SizedBox(height: 8),
+        ],
+      ),
+    );
+  }
+}