refactor(frontend): 优化参与记录和贡献值页面的文案显示

参与记录页面（planting_records_page.dart）:
- 将状态 "已开始挖矿" 改为 "已开始"
- 将 "xx棵" 改为 "xx个"
- 将 "单棵算力" 改为 "单个算力"

贡献值页面（contribution_page.dart）:
- 将贡献值明细中的 "本人种植" 改为 "本人"
- 移除 "已解锁上级" 和 "已解锁下级" 后的 "级" 字后缀

实体类（planting_record.dart）:
- 同步更新状态显示文案 "已开始挖矿" → "已开始"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mining-app/lib/domain/entities/planting_record.dart

@@ -56,7 +56,7 @@ class PlantingRecord extends Equatable {
       case PlantingStatus.fundAllocated:
         return '资金已分配';
       case PlantingStatus.miningEnabled:
-        return '已开始挖矿';
+        return '已开始';
       case PlantingStatus.cancelled:
         return '已取消';
       case PlantingStatus.expired:

frontend/mining-app/lib/presentation/pages/contribution/contribution_page.dart

@@ -415,7 +415,7 @@ class ContributionPage extends ConsumerWidget {
                 _buildDetailSummaryRow(
                   icon: Icons.eco_outlined,
                   iconColor: _orange,
-                  title: '本人种植',
+                  title: '本人',
                   subtitle: '个人参与产生的贡献值',
                   amount: contribution?.personalContribution ?? '0',
                   hideAmounts: hideAmounts,
@@ -467,7 +467,7 @@ class ContributionPage extends ConsumerWidget {
             crossAxisAlignment: CrossAxisAlignment.start,
             children: const [
               ShimmerText(
-                placeholder: '本人种植',
+                placeholder: '本人',
                 style: TextStyle(fontSize: 14, fontWeight: FontWeight.w500, color: _darkText),
               ),
               SizedBox(height: 2),
@@ -558,7 +558,7 @@ class ContributionPage extends ConsumerWidget {
               _buildTeamStatItem(
                 '已解锁上级',
                 '15',
-                '级',
+                '',
                 isLoading,
               ),
             ],
@@ -570,7 +570,7 @@ class ContributionPage extends ConsumerWidget {
               _buildTeamStatItem(
                 '已解锁下级',
                 contribution?.unlockedLevelDepth.toString(),
-                '级',
+                '',
                 isLoading,
               ),
               const SizedBox(width: 16),

frontend/mining-app/lib/presentation/pages/profile/planting_records_page.dart

@@ -341,13 +341,13 @@ class _PlantingRecordsPageState extends ConsumerState<PlantingRecordsPage> {
             ),
             const SizedBox(height: 12),
 
-            // 第二行：参与数量 + 单棵算力 + 总算力
+            // 第二行：参与数量 + 单个算力 + 总算力
             Wrap(
               spacing: 12,
               runSpacing: 8,
               children: [
-                _buildInfoItem('参与数量', '${record.treeCount}棵'),
-                _buildInfoItem('单棵算力', formatAmount(record.contributionPerTree)),
+                _buildInfoItem('参与数量', '${record.treeCount}个'),
+                _buildInfoItem('单个算力', formatAmount(record.contributionPerTree)),
                 _buildInfoItem('总算力', formatAmount(record.totalContribution), isHighlight: true),
               ],
             ),
@@ -404,7 +404,7 @@ class _PlantingRecordsPageState extends ConsumerState<PlantingRecordsPage> {
         borderRadius: BorderRadius.circular(4),
       ),
       child: Text(
-        status.toString().split('.').last == 'miningEnabled' ? '已开始挖矿' : _getStatusText(status),
+        status.toString().split('.').last == 'miningEnabled' ? '已开始' : _getStatusText(status),
         style: TextStyle(fontSize: 11, fontWeight: FontWeight.w500, color: textColor),
       ),
     );
@@ -419,7 +419,7 @@ class _PlantingRecordsPageState extends ConsumerState<PlantingRecordsPage> {
       case PlantingStatus.fundAllocated:
         return '资金已分配';
       case PlantingStatus.miningEnabled:
-        return '已开始挖矿';
+        return '已开始';
       case PlantingStatus.cancelled:
         return '已取消';
       case PlantingStatus.expired: