修复行情页BTC/ETH价格文字溢出：用FittedBox自适应缩放

flutter_monisuo/lib/ui/pages/home/hot_coins_section.dart

@@ -144,9 +144,13 @@ class _CoinRow extends StatelessWidget {
           Column(
             crossAxisAlignment: CrossAxisAlignment.end,
             children: [
-              Text(
-                price,
-                style: AppTextStyles.numberMedium(context),
+              FittedBox(
+                fit: BoxFit.scaleDown,
+                alignment: Alignment.centerRight,
+                child: Text(
+                  price,
+                  style: AppTextStyles.numberMedium(context),
+                ),
               ),
               Text(
                 change,

flutter_monisuo/lib/ui/pages/trade/components/price_card.dart

@@ -37,9 +37,15 @@ class PriceCard extends StatelessWidget {
           // 價格行：大號價格 + 漲跌幅徽章
           Row(
             children: [
-              Text(
-                coin.formattedPrice,
-                style: AppTextStyles.numberLarge(context).copyWith(fontSize: 32),
+              Flexible(
+                child: FittedBox(
+                  fit: BoxFit.scaleDown,
+                  alignment: Alignment.centerLeft,
+                  child: Text(
+                    coin.formattedPrice,
+                    style: AppTextStyles.numberLarge(context).copyWith(fontSize: 32),
+                  ),
+                ),
               ),
               const SizedBox(width: AppSpacing.sm),
               // 漲跌幅徽章 - 圓角sm，漲綠背景