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

query_fund_accounts.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+
+BASE_URL="http://localhost:5010"
+
+# 1. 登录
+echo "================================"
+echo "查询用户资金账户数据"
+echo "================================"
+echo ""
+
+LOGIN_RESPONSE=$(curl -s -X POST "$BASE_URL/admin/login" \
+  -H "Content-Type: application/json" \
+  -d '{"username":"admin","password":"admin123"}')
+
+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"
+    echo "$LOGIN_RESPONSE"
+    exit 1
+fi
+
+echo "✅ 登录成功"
+echo ""
+
+# 2. 查询用户列表
+echo "步骤1: 查询用户列表..."
+USER_LIST=$(curl -s "$BASE_URL/admin/user/list?pageNum=1&pageSize=100" \
+  -H "Authorization: Bearer $TOKEN")
+
+echo "$USER_LIST" | python3 -m json.tool 2>/dev/null || echo "$USER_LIST"
+echo ""
+
+# 提取用户ID列表
+USER_IDS=$(echo "$USER_LIST" | python3 -c "
+import sys, json
+data = json.load(sys.stdin)
+if data.get('success') and data['data'].get('list'):
+    for user in data['data']['list']:
+        print(user['id'])
+" 2>/dev/null)
+
+if [ -z "$USER_IDS" ]; then
+    echo "❌ 没有找到用户"
+    exit 1
+fi
+
+# 3. 查询每个用户的资金账户
+echo "步骤2: 查询每个用户的资金账户..."
+echo ""
+
+for USER_ID in $USER_IDS; do
+    echo "================================"
+    echo "用户ID: $USER_ID"
+    echo "================================"
+    
+    USER_DETAIL=$(curl -s "$BASE_URL/admin/user/detail?userId=$USER_ID" \
+      -H "Authorization: Bearer $TOKEN")
+    
+    echo "$USER_DETAIL" | python3 -m json.tool 2>/dev/null || echo "$USER_DETAIL"
+    echo ""
+done
+
+echo "================================"
+echo "查询完成"
+echo "================================"