revert(app): 回滚 C2C 页面的卖出限制

C2C 卖出的是积分值，不是积分股，不受预种卖出限制约束。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/mining-app/lib/presentation/pages/c2c/c2c_publish_page.dart

@@ -711,10 +711,9 @@ class _C2cPublishPageState extends ConsumerState<C2cPublishPage> {
     final isSell = _selectedType == 1;
     final capabilities = ref.watch(capabilitiesProvider).valueOrNull ?? CapabilityMap.defaultAll();
     final c2cEnabled = capabilities.c2cEnabled;
-    final isSellRestricted = isSell && (ref.watch(sellRestrictionProvider).valueOrNull ?? false);
 
     // #11: 价格固定为1，数量最小为1
-    bool isValid = c2cEnabled && !isSellRestricted && quantity >= 1;
+    bool isValid = c2cEnabled && quantity >= 1;
     if (isSell) {
       // 如果选择了其他支付方式，还需要填写收款账号和姓名
       if (_selectedPaymentMethods.any((m) => m != 'GREEN_POINTS')) {
@@ -726,34 +725,12 @@ class _C2cPublishPageState extends ConsumerState<C2cPublishPage> {
 
     return Padding(
       padding: const EdgeInsets.symmetric(horizontal: 16),
-      child: Column(
+      child: SizedBox(
-        children: [
-          if (isSellRestricted)
-            Container(
-              width: double.infinity,
-              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
-              margin: const EdgeInsets.only(bottom: 8),
-              decoration: BoxDecoration(
-                color: _red.withOpacity(0.08),
-                borderRadius: BorderRadius.circular(8),
-                border: Border.all(color: _red.withOpacity(0.3)),
-              ),
-              child: const Text(
-                '预种积分股暂时不可卖出，请先完成预种合并（满5份合成1棵树后即可卖出）',
-                style: TextStyle(fontSize: 12, color: _red),
-                textAlign: TextAlign.center,
-              ),
-            ),
-          SizedBox(
         width: double.infinity,
         height: 50,
         child: ElevatedButton(
           onPressed: isValid && !c2cState.isLoading
               ? _handlePublish
-                  : isSellRestricted
-                      ? () => ScaffoldMessenger.of(context).showSnackBar(
-                            const SnackBar(content: Text('预种积分股暂时不可卖出，请先完成预种合并'), backgroundColor: _red),
-                          )
               : !c2cEnabled
                   ? () => ScaffoldMessenger.of(context).showSnackBar(
                         const SnackBar(content: Text('您的C2C交易功能已被限制'), backgroundColor: _red),
@@ -786,8 +763,6 @@ class _C2cPublishPageState extends ConsumerState<C2cPublishPage> {
                 ),
         ),
       ),
-        ],
-      ),
     );
   }