fix: 修复Flutter资产页面API接口字段名称不匹配问题

主要修改:
1. AssetService.java - 修改getOverview()方法返回字段
   - totalAssets → totalAsset (总资产)
   - tradeValue → tradeBalance (交易余额)
   - 新增 totalProfit 字段 (总盈亏)
   - 移除 fundFrozen 和 positions 字段 (Flutter不需要)

2. 新增诊断工具和文档:
   - ASSET_API_DIAGNOSIS.md - API接口问题诊断报告
   - DATABASE_SCHEMA.md - 数据库表结构说明
   - test_asset_api.sh - API接口测试脚本
   - query_fund_accounts.sh - 用户资金账户查询脚本
   - fix_asset_api.sh - 自动修复脚本

修复后API返回格式:
{
  "totalAsset": 15500.0,      // 总资产
  "fundBalance": 15500.0,     // 资金余额
  "tradeBalance": 0,          // 交易余额
  "totalProfit": 0            // 总盈亏
}

影响范围:
- Flutter前端资产页面现在可以正确显示用户资产
- 充值审批后余额正确更新
- 资金账户数据查询正常

test_asset_api.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+
+BASE_URL="http://localhost:5010"
+
+echo "================================"
+echo "测试资产API接口"
+echo "================================"
+
+# 1. 用户登录
+echo -e "\n步骤1: 用户登录..."
+LOGIN_RESPONSE=$(curl -s -X POST "$BASE_URL/api/user/login" \
+  -H "Content-Type: application/json" \
+  -d '{"username":"abcd","password":"abcd123"}')
+
+echo "登录响应: $LOGIN_RESPONSE"
+TOKEN=$(echo $LOGIN_RESPONSE | python3 -c "
+import sys, json
+data = json.load(sys.stdin)
+if data.get('success'):
+    print(data['data']['token'])
+" 2>/dev/null)
+
+if [ -z "$TOKEN" ]; then
+    echo "❌ 登录失败"
+    exit 1
+fi
+
+echo "✅ 登录成功"
+echo "Token: ${TOKEN:0:30}..."
+
+# 2. 测试资产总览接口
+echo -e "\n================================"
+echo "测试 /api/asset/overview 接口"
+echo "================================"
+OVERVIEW_RESPONSE=$(curl -s "$BASE_URL/api/asset/overview" \
+  -H "Authorization: Bearer $TOKEN")
+
+echo "$OVERVIEW_RESPONSE" | python3 -m json.tool 2>/dev/null || echo "$OVERVIEW_RESPONSE"
+
+# 分析字段
+echo -e "\n字段分析:"
+echo "$OVERVIEW_RESPONSE" | python3 -c "
+import sys, json
+data = json.load(sys.stdin)
+if data.get('success') and data.get('data'):
+    print('后端返回的字段:')
+    for key in data['data'].keys():
+        print(f'  - {key}: {type(data[\"data\"][key]).__name__}')
+    print('\nFlutter期望的字段:')
+    print('  - totalAsset (总资产)')
+    print('  - fundBalance (资金余额)')
+    print('  - tradeBalance (交易余额)')
+    print('  - totalProfit (总盈亏)')
+"
+
+# 3. 测试资金账户接口
+echo -e "\n================================"
+echo "测试 /api/asset/fund 接口"
+echo "================================"
+FUND_RESPONSE=$(curl -s "$BASE_URL/api/asset/fund" \
+  -H "Authorization: Bearer $TOKEN")
+
+echo "$FUND_RESPONSE" | python3 -m json.tool 2>/dev/null || echo "$FUND_RESPONSE"
+
+# 4. 测试交易账户接口
+echo -e "\n================================"
+echo "测试 /api/asset/trade 接口"
+echo "================================"
+TRADE_RESPONSE=$(curl -s "$BASE_URL/api/asset/trade" \
+  -H "Authorization: Bearer $TOKEN")
+
+echo "$TRADE_RESPONSE" | python3 -m json.tool 2>/dev/null || echo "$TRADE_RESPONSE"
+
+echo -e "\n================================"
+echo "问题诊断"
+echo "================================"
+echo "$OVERVIEW_RESPONSE" | python3 -c "
+import sys, json
+data = json.load(sys.stdin)
+if data.get('success') and data.get('data'):
+    backend_fields = set(data['data'].keys())
+    flutter_expected = {'totalAsset', 'fundBalance', 'tradeBalance', 'totalProfit'}
+    
+    print('后端返回字段:', sorted(backend_fields))
+    print('Flutter期望字段:', sorted(flutter_expected))
+    print()
+    
+    missing = flutter_expected - backend_fields
+    extra = backend_fields - flutter_expected
+    
+    if missing:
+        print('❌ 缺失字段:', sorted(missing))
+    if extra:
+        print('⚠️  额外字段:', sorted(extra))
+    
+    # 检查字段名称不匹配
+    if 'totalAssets' in backend_fields and 'totalAsset' in flutter_expected:
+        print('⚠️  字段名称不匹配: totalAssets vs totalAsset')
+    if 'tradeValue' in backend_fields and 'tradeBalance' in flutter_expected:
+        print('⚠️  字段名称不匹配: tradeValue vs tradeBalance')
+    if 'totalProfit' not in backend_fields:
+        print('⚠️  缺失字段: totalProfit')
+"
+
+echo "================================"
+echo "测试完成"
+echo "================================"