feat(mobile): add close button to planting confirm dialog

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mobile-app/lib/features/planting/presentation/widgets/planting_confirm_dialog.dart

@@ -84,6 +84,11 @@ class _PlantingConfirmDialogState extends State<PlantingConfirmDialog> {
     }
   }
 
+  /// 关闭弹窗
+  void _handleClose() {
+    Navigator.pop(context, false);
+  }
+
   @override
   Widget build(BuildContext context) {
     return Dialog(
@@ -104,27 +109,53 @@ class _PlantingConfirmDialogState extends State<PlantingConfirmDialog> {
             ),
           ],
         ),
-        child: Padding(
+        child: Stack(
-          padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 32),
+          children: [
-          child: Column(
+            // 主内容
-            mainAxisSize: MainAxisSize.min,
+            Padding(
-            children: [
+              padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 32),
-              // 警告图标
+              child: Column(
-              _buildWarningIcon(),
+                mainAxisSize: MainAxisSize.min,
-              const SizedBox(height: 4),
+                children: [
-              // 标题
+                  // 警告图标
-              _buildTitle(),
+                  _buildWarningIcon(),
-              const SizedBox(height: 4),
+                  const SizedBox(height: 4),
-              // 内容说明
+                  // 标题
-              _buildContent(),
+                  _buildTitle(),
-              const SizedBox(height: 4),
+                  const SizedBox(height: 4),
-              // 倒计时提示
+                  // 内容说明
-              _buildCountdownText(),
+                  _buildContent(),
-              const SizedBox(height: 4),
+                  const SizedBox(height: 4),
-              // 确认按钮
+                  // 倒计时提示
-              _buildConfirmButton(),
+                  _buildCountdownText(),
-            ],
+                  const SizedBox(height: 4),
-          ),
+                  // 确认按钮
+                  _buildConfirmButton(),
+                ],
+              ),
+            ),
+            // 右上角关闭按钮
+            Positioned(
+              top: 8,
+              right: 8,
+              child: GestureDetector(
+                onTap: _handleClose,
+                child: Container(
+                  width: 32,
+                  height: 32,
+                  decoration: BoxDecoration(
+                    color: const Color(0x0D000000),
+                    borderRadius: BorderRadius.circular(16),
+                  ),
+                  child: const Icon(
+                    Icons.close,
+                    size: 18,
+                    color: Color(0xFF8B5A2B),
+                  ),
+                ),
+              ),
+            ),
+          ],
         ),
       ),
     );