fix: 优化充值提现和划转界面

- 充值提现弹框: 去掉透明效果，改为实心背景，确保可读性
- 划转界面: 重构为币安风格，账户选择更清晰，交互更自然
- 交易界面: 充值/提现/划转按钮去掉图标，只保留文字
- 整体提升专业金融感

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

@@ -294,7 +294,6 @@ class _FundAccountCard extends StatelessWidget {
                 child: NeonButton(
                   text: '充值',
                   type: NeonButtonType.tertiary,
-                  icon: Icons.add,
                   onPressed: () => _showDepositDialog(context),
                   height: 44,
                   showGlow: false,
@@ -305,7 +304,6 @@ class _FundAccountCard extends StatelessWidget {
                 child: NeonButton(
                   text: '提现',
                   type: NeonButtonType.secondary,
-                  icon: Icons.remove,
                   onPressed: () => _showWithdrawDialog(context, fund?.balance),
                   height: 44,
                   showGlow: false,
@@ -316,7 +314,6 @@ class _FundAccountCard extends StatelessWidget {
                 child: NeonButton(
                   text: '划转',
                   type: NeonButtonType.outline,
-                  icon: Icons.swap_horiz,
                   onPressed: () => _navigateToTransfer(context),
                   height: 44,
                   showGlow: false,