feat(mobile): allow manual input for planting quantity

- Replace static text with editable TextField for quantity
- Add warning when input exceeds max quantity based on balance
- Sync +/- buttons with input field value

🤖 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/pages/planting_quantity_page.dart

@@ -34,10 +34,58 @@ class _PlantingQuantityPageState extends ConsumerState<PlantingQuantityPage> {
   /// 加载错误信息
   String? _errorMessage;
 
+  /// 数量输入框控制器
+  final TextEditingController _quantityController = TextEditingController();
+
+  /// 数量输入框焦点
+  final FocusNode _quantityFocusNode = FocusNode();
+
+  /// 是否显示超出警告
+  bool _showExceedWarning = false;
+
   @override
   void initState() {
     super.initState();
     _loadBalance();
+    _quantityController.addListener(_onQuantityChanged);
+  }
+
+  @override
+  void dispose() {
+    _quantityController.removeListener(_onQuantityChanged);
+    _quantityController.dispose();
+    _quantityFocusNode.dispose();
+    super.dispose();
+  }
+
+  /// 输入框数量变化监听
+  void _onQuantityChanged() {
+    final text = _quantityController.text;
+    if (text.isEmpty) {
+      setState(() {
+        _quantity = 0;
+        _showExceedWarning = false;
+      });
+      return;
+    }
+
+    final inputQty = int.tryParse(text) ?? 0;
+    setState(() {
+      _quantity = inputQty;
+      _showExceedWarning = inputQty > _maxQuantity;
+    });
+  }
+
+  /// 更新输入框显示的数量
+  void _updateQuantityText(int qty) {
+    final newText = qty > 0 ? qty.toString() : '';
+    if (_quantityController.text != newText) {
+      _quantityController.text = newText;
+      // 将光标移到末尾
+      _quantityController.selection = TextSelection.fromPosition(
+        TextPosition(offset: newText.length),
+      );
+    }
   }
 
   /// 加载用户余额
@@ -69,7 +117,10 @@ class _PlantingQuantityPageState extends ConsumerState<PlantingQuantityPage> {
         // 自动填入最大可认种数量，至少为1（如果有足够余额）
         _quantity = maxQty > 0 ? maxQty : 0;
         _isLoading = false;
+        _showExceedWarning = false;
       });
+      // 更新输入框
+      _updateQuantityText(_quantity);
     } catch (e) {
       debugPrint('加载余额失败: $e');
       setState(() {
@@ -89,14 +140,24 @@ class _PlantingQuantityPageState extends ConsumerState<PlantingQuantityPage> {
   /// 减少数量
   void _decreaseQuantity() {
     if (_quantity > 1) {
-      setState(() => _quantity--);
+      final newQty = _quantity - 1;
+      setState(() {
+        _quantity = newQty;
+        _showExceedWarning = false;
+      });
+      _updateQuantityText(newQty);
     }
   }
 
   /// 增加数量
   void _increaseQuantity() {
     if (_quantity < _maxQuantity) {
-      setState(() => _quantity++);
+      final newQty = _quantity + 1;
+      setState(() {
+        _quantity = newQty;
+        _showExceedWarning = false;
+      });
+      _updateQuantityText(newQty);
     }
   }
 
@@ -403,55 +464,139 @@ class _PlantingQuantityPageState extends ConsumerState<PlantingQuantityPage> {
 
   /// 构建数量选择器
   Widget _buildQuantitySelector() {
-    return Container(
+    return Column(
-      width: double.infinity,
+      children: [
-      padding: const EdgeInsets.all(24),
+        Container(
-      decoration: BoxDecoration(
+          width: double.infinity,
-        color: const Color(0x99FFFFFF),
+          padding: const EdgeInsets.all(24),
-        borderRadius: BorderRadius.circular(12),
+          decoration: BoxDecoration(
-        boxShadow: const [
+            color: const Color(0x99FFFFFF),
-          BoxShadow(
+            borderRadius: BorderRadius.circular(12),
-            color: Color(0x1A000000),
+            boxShadow: const [
-            blurRadius: 6,
+              BoxShadow(
-            offset: Offset(0, 4),
+                color: Color(0x1A000000),
+                blurRadius: 6,
+                offset: Offset(0, 4),
+              ),
+              BoxShadow(
+                color: Color(0x1A000000),
+                blurRadius: 4,
+                offset: Offset(0, 2),
+              ),
+            ],
           ),
-          BoxShadow(
+          child: Row(
-            color: Color(0x1A000000),
+            mainAxisAlignment: MainAxisAlignment.center,
-            blurRadius: 4,
+            children: [
-            offset: Offset(0, 2),
+              // 减少按钮
+              _buildQuantityButton(
+                icon: '-',
+                onTap: _canDecrease ? _decreaseQuantity : null,
+                enabled: _canDecrease,
+              ),
+              const SizedBox(width: 24),
+              // 数量输入框
+              SizedBox(
+                width: 80,
+                child: TextField(
+                  controller: _quantityController,
+                  focusNode: _quantityFocusNode,
+                  keyboardType: TextInputType.number,
+                  textAlign: TextAlign.center,
+                  style: TextStyle(
+                    fontSize: 36,
+                    fontFamily: 'Inter',
+                    fontWeight: FontWeight.w400,
+                    height: 1.5,
+                    color: _showExceedWarning
+                        ? const Color(0xFFE65100)
+                        : const Color(0xFF5D4037),
+                  ),
+                  decoration: InputDecoration(
+                    border: OutlineInputBorder(
+                      borderRadius: BorderRadius.circular(8),
+                      borderSide: BorderSide(
+                        color: _showExceedWarning
+                            ? const Color(0xFFE65100)
+                            : const Color(0xFFD4AF37),
+                        width: 1,
+                      ),
+                    ),
+                    enabledBorder: OutlineInputBorder(
+                      borderRadius: BorderRadius.circular(8),
+                      borderSide: BorderSide(
+                        color: _showExceedWarning
+                            ? const Color(0xFFE65100)
+                            : const Color(0xFFD4AF37),
+                        width: 1,
+                      ),
+                    ),
+                    focusedBorder: OutlineInputBorder(
+                      borderRadius: BorderRadius.circular(8),
+                      borderSide: BorderSide(
+                        color: _showExceedWarning
+                            ? const Color(0xFFE65100)
+                            : const Color(0xFFD4AF37),
+                        width: 2,
+                      ),
+                    ),
+                    contentPadding: const EdgeInsets.symmetric(
+                      horizontal: 8,
+                      vertical: 8,
+                    ),
+                    isDense: true,
+                  ),
+                ),
+              ),
+              const SizedBox(width: 24),
+              // 增加按钮
+              _buildQuantityButton(
+                icon: '+',
+                onTap: _canIncrease ? _increaseQuantity : null,
+                enabled: _canIncrease,
+              ),
+            ],
           ),
-        ],
+        ),
-      ),
+        // 超出警告提示
-      child: Row(
+        if (_showExceedWarning)
-        mainAxisAlignment: MainAxisAlignment.center,
+          Padding(
-        children: [
+            padding: const EdgeInsets.only(top: 12),
-          // 减少按钮
+            child: Container(
-          _buildQuantityButton(
+              width: double.infinity,
-            icon: '-',
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
-            onTap: _canDecrease ? _decreaseQuantity : null,
+              decoration: BoxDecoration(
-            enabled: _canDecrease,
+                color: const Color(0xFFFFF3E0),
-          ),
+                borderRadius: BorderRadius.circular(8),
-          const SizedBox(width: 38),
+                border: Border.all(
-          // 数量显示
+                  color: const Color(0xFFE65100),
-          Text(
+                  width: 1,
-            '$_quantity',
+                ),
-            style: const TextStyle(
+              ),
-              fontSize: 36,
+              child: Row(
-              fontFamily: 'Inter',
+                children: [
-              fontWeight: FontWeight.w400,
+                  const Icon(
-              height: 1.5,
+                    Icons.warning_amber_rounded,
-              color: Color(0xFF5D4037),
+                    color: Color(0xFFE65100),
+                    size: 20,
+                  ),
+                  const SizedBox(width: 8),
+                  Expanded(
+                    child: Text(
+                      '输入数量 $_quantity 超过最大可认种数量 $_maxQuantity，请调整',
+                      style: const TextStyle(
+                        fontSize: 14,
+                        fontFamily: 'Inter',
+                        height: 1.5,
+                        color: Color(0xFFE65100),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
             ),
           ),
-          const SizedBox(width: 38),
+      ],
-          // 增加按钮
-          _buildQuantityButton(
-            icon: '+',
-            onTap: _canIncrease ? _increaseQuantity : null,
-            enabled: _canIncrease,
-          ),
-        ],
-      ),
     );
   }