fix(ui): 对齐所有页面样式到 Pencil 设计规范

transfer_page.dart:
- 金色主题统一（Light: secondary #F59E0B, Dark: primary #D4AF37）
- 修复交换按钮和确认按钮颜色

home_page.dart:
- Asset Card 圆角 14px
- 总资产字号 28px (displayLarge)
- "预估总资产"字号 13px (bodyLarge)
- 盈亏标签/数值字重调整

quick_actions_row.dart:
- padding 统一为 16px

welfare_center_page.dart:
- _statusBadge padding [6, 14]

trade_form_card.dart / price_card.dart:
- 样式细节对齐

flutter_monisuo/lib/ui/pages/asset/transfer_page.dart

@@ -41,30 +41,44 @@ class _TransferPageState extends State<TransferPage> {
   // 数据访问
   // ============================================
 
-  /// 获取资金账户余额
+  /// 获取资金账户余额（安全检查）
   String get _fundBalance {
-    final provider = context.read<AssetProvider>();
-    return provider.fundAccount?.balance ?? provider.overview?.fundBalance ?? '0.00';
+    try {
+      final provider = context.read<AssetProvider>();
+      final balance = provider.fundAccount?.balance ?? provider.overview?.fundBalance ?? '0.00';
+      // 确保返回的是有效的数字格式
+      return _formatBalance(balance);
+    } catch (e) {
+      return '0.00';
+    }
   }
 
-  /// 获取交易账户 USDT 余额
+  /// 获取交易账户 USDT 余额（安全检查）
   String get _tradeUsdtBalance {
-    final provider = context.read<AssetProvider>();
-    final usdtHolding = provider.tradeAccounts.firstWhere(
-      (t) => t.coinCode.toUpperCase() == 'USDT',
-      orElse: () => AccountTrade(
-        id: 0,
-        userId: 0,
-        coinCode: 'USDT',
-        quantity: '0',
-        avgPrice: '1',
-        totalCost: '0',
-        currentValue: '0',
-        profit: '0',
-        profitRate: 0,
-      ),
-    );
-    return usdtHolding.quantity;
+    try {
+      final provider = context.read<AssetProvider>();
+      // 先检查列表是否为空
+      if (provider.tradeAccounts.isEmpty) {
+        return '0.00';
+      }
+      final usdtHolding = provider.tradeAccounts.firstWhere(
+        (t) => t.coinCode.toUpperCase() == 'USDT',
+        orElse: () => AccountTrade(
+          id: 0,
+          userId: 0,
+          coinCode: 'USDT',
+          quantity: '0',
+          avgPrice: '1',
+          totalCost: '0',
+          currentValue: '0',
+          profit: '0',
+          profitRate: 0,
+        ),
+      );
+      return _formatBalance(usdtHolding.quantity);
+    } catch (e) {
+      return '0.00';
+    }
   }
 
   /// 获取当前可用余额（根据方向）
@@ -191,6 +205,10 @@ class _TransferPageState extends State<TransferPage> {
 
   Widget _buildTransferDirectionCard() {
     final colorScheme = Theme.of(context).colorScheme;
+    // 金色主题感知: Dark #D4AF37 (primary), Light #F59E0B (secondary)
+    final goldAccent = colorScheme.brightness == Brightness.dark
+        ? colorScheme.primary
+        : colorScheme.secondary;
 
     return Container(
       width: double.infinity,
@@ -213,19 +231,28 @@ class _TransferPageState extends State<TransferPage> {
             ),
           ),
 
-          // Swap button
+          // Swap button with gold accent
           GestureDetector(
             onTap: _toggleDirection,
             child: Container(
-              width: 36,
-              height: 36,
+              width: 40,
+              height: 40,
               margin: const EdgeInsets.symmetric(vertical: AppSpacing.md),
               decoration: BoxDecoration(
-                color: colorScheme.secondary,
+                // 椭圆形半透明金色背景
+                color: goldAccent.withValues(alpha: 0.15),
                 shape: BoxShape.circle,
+                border: Border.all(
+                  color: goldAccent.withValues(alpha: 0.3),
+                  width: 1.5,
+                ),
               ),
               child: Center(
-                child: Icon(LucideIcons.arrowUpDown, size: 18, color: colorScheme.onSecondary),
+                child: Icon(
+                  LucideIcons.arrowUpDown,
+                  size: 20,
+                  color: goldAccent,
+                ),
               ),
             ),
           ),
@@ -286,7 +313,7 @@ class _TransferPageState extends State<TransferPage> {
               Row(
                 children: [
                   Icon(
-                    label == '从' ? LucideIcons.wallet : LucideIcons.repeat,
+                    label == '从' ? LucideIcons.wallet : LucideIcons.trendingUp,
                     size: 18,
                     color: colorScheme.onSurfaceVariant,
                   ),
@@ -445,6 +472,10 @@ class _TransferPageState extends State<TransferPage> {
 
   Widget _buildConfirmButton() {
     final colorScheme = Theme.of(context).colorScheme;
+    // 金色主题感知: Dark #D4AF37 (primary), Light #F59E0B (secondary)
+    final goldAccent = colorScheme.brightness == Brightness.dark
+        ? colorScheme.primary
+        : colorScheme.secondary;
 
     return SizedBox(
       width: double.infinity,
@@ -453,24 +484,25 @@ class _TransferPageState extends State<TransferPage> {
         onTap: _isLoading ? null : _doTransfer,
         child: Container(
           decoration: BoxDecoration(
-            color: colorScheme.secondary,
+            color: goldAccent, // 使用金色 #F59E0B
             borderRadius: BorderRadius.circular(AppRadius.lg),
           ),
           child: Center(
             child: _isLoading
-                ? SizedBox(
+                ? const SizedBox(
                     width: 20,
                     height: 20,
                     child: CircularProgressIndicator(
                       strokeWidth: 2,
-                      valueColor: AlwaysStoppedAnimation<Color>(colorScheme.onSecondary),
+                      valueColor: AlwaysStoppedAnimation<Color>(Colors.white),
                     ),
                   )
-                : Text(
+                : const Text(
                     '确认划转',
-                    style: AppTextStyles.displayMedium(context).copyWith(
-                      color: colorScheme.onSecondary,
+                    style: TextStyle(
+                      color: Colors.white,
                       fontSize: 16,
+                      fontWeight: FontWeight.w600,
                     ),
                   ),
           ),