feat: 优化交易账户和币种选择功能

- 交易账户卡片添加总市值显示和持仓列表
- 持仓列表USDT自动排在最上面
- 交易页面添加币种选择弹窗功能
- 行情页面点击币种跳转到交易页面
- 支持从外部传入选中币种参数

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

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

@@ -63,7 +63,10 @@ class _AssetPageState extends State<AssetPage> with AutomaticKeepAliveClientMixi
                   SizedBox(height: AppSpacing.md),
                   _activeTab == 0
                       ? _FundAccountCard(provider: provider)
-                      : _TradeAccountCard(holdings: provider.holdings),
+                      : _TradeAccountCard(
+                          holdings: provider.holdings,
+                          tradeBalance: provider.overview?.tradeBalance,
+                        ),
                 ],
               ),
             ),
@@ -327,40 +330,116 @@ class _FundAccountCard extends StatelessWidget {
 /// 交易账户卡片 - Glass Panel 风格
 class _TradeAccountCard extends StatelessWidget {
   final List holdings;
+  final String? tradeBalance;
 
-  const _TradeAccountCard({required this.holdings});
+  const _TradeAccountCard({required this.holdings, this.tradeBalance});
 
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
+    final isDark = Theme.of(context).brightness == Brightness.dark;
+
+    // 计算总市值（所有持仓折算成USDT）
+    double totalValue = 0;
+    for (var h in holdings) {
+      final value = double.tryParse(h.currentValue?.toString() ?? '0') ?? 0;
+      totalValue += value;
+    }
+
+    // 对持仓进行排序：USDT 放在最上面
+    final sortedHoldings = List.from(holdings);
+    sortedHoldings.sort((a, b) {
+      final codeA = (a.coinCode ?? a['coinCode'] ?? '').toString().toUpperCase();
+      final codeB = (b.coinCode ?? b['coinCode'] ?? '').toString().toUpperCase();
+      if (codeA == 'USDT') return -1;
+      if (codeB == 'USDT') return 1;
+      return 0;
+    });
 
     return GlassPanel(
       padding: AppSpacing.cardPadding,
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
+          // 标题行
+          Row(
+            mainAxisAlignment: MainAxisAlignment.spaceBetween,
+            children: [
+              Row(
+                children: [
+                  Container(
+                    width: 36,
+                    height: 36,
+                    decoration: BoxDecoration(
+                      color: colorScheme.primary.withOpacity(0.1),
+                      borderRadius: BorderRadius.circular(AppRadius.md),
+                    ),
+                    child: Icon(
+                      LucideIcons.trendingUp,
+                      size: 18,
+                      color: colorScheme.primary,
+                    ),
+                  ),
+                  SizedBox(width: AppSpacing.sm),
+                  Text(
+                    '交易账户',
+                    style: GoogleFonts.spaceGrotesk(
+                      fontSize: 16,
+                      fontWeight: FontWeight.bold,
+                      color: colorScheme.onSurface,
+                    ),
+                  ),
+                ],
+              ),
+              Icon(
+                LucideIcons.chevronRight,
+                size: 14,
+                color: colorScheme.primary,
+              ),
+            ],
+          ),
+          SizedBox(height: AppSpacing.md),
+          // 总市值
           Text(
-            '持仓列表',
+            '总市值 (USDT)',
+            style: TextStyle(
+              fontSize: 11,
+              color: colorScheme.onSurfaceVariant,
+            ),
+          ),
+          SizedBox(height: AppSpacing.xs),
+          Text(
+            totalValue.toStringAsFixed(2),
             style: GoogleFonts.spaceGrotesk(
-              fontSize: 16,
+              fontSize: 28,
               fontWeight: FontWeight.bold,
               color: colorScheme.onSurface,
             ),
           ),
+          SizedBox(height: AppSpacing.lg),
+          // 持仓列表标题
+          Text(
+            '持仓列表',
+            style: GoogleFonts.spaceGrotesk(
+              fontSize: 14,
+              fontWeight: FontWeight.w600,
+              color: colorScheme.onSurfaceVariant,
+            ),
+          ),
           SizedBox(height: AppSpacing.md),
-          if (holdings.isEmpty)
+          if (sortedHoldings.isEmpty)
             const _EmptyState(icon: LucideIcons.wallet, message: '暂无持仓')
           else
             ListView.separated(
               shrinkWrap: true,
               physics: const NeverScrollableScrollPhysics(),
-              itemCount: holdings.length,
+              itemCount: sortedHoldings.length,
               separatorBuilder: (_, __) => Container(
                 margin: EdgeInsets.only(left: 56),
                 height: 1,
                 color: AppColorScheme.glassPanelBorder,
               ),
-              itemBuilder: (context, index) => _HoldingItem(holding: holdings[index]),
+              itemBuilder: (context, index) => _HoldingItem(holding: sortedHoldings[index]),
             ),
         ],
       ),