feat: 前端充值信息展示 + 文档更新

- 表格新增充值电量列, 汇总卡新增充值统计

- README 更新精确计算说明与 XF_PRICE 配置

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

go/static/index.html

@@ -42,7 +42,9 @@
         <div class="summary-item"><div class="summary-value" id="sRecordCount">--</div><div class="summary-label">记录天数</div></div>
         <div class="summary-item"><div class="summary-value" id="sTotalUsage">--</div><div class="summary-label">月总耗电(度)</div></div>
         <div class="summary-item"><div class="summary-value" id="sAvgUsage">--</div><div class="summary-label">日均耗电(度)</div></div>
-        <div class="summary-item"><div class="summary-value" id="sRecharge">--</div><div class="summary-label">疑似充值(天)</div></div>
+        <div class="summary-item"><div class="summary-value" id="sRecharge">--</div><div class="summary-label">充值(次)</div></div>
+        <div class="summary-item"><div class="summary-value" id="sRechargeKwh">--</div><div class="summary-label">充值电量(度)</div></div>
+        <div class="summary-item"><div class="summary-value" id="sRechargeMoney">--</div><div class="summary-label">充值金额(元)</div></div>
         <div class="summary-item"><div class="summary-value" id="sStartSurplus">--</div><div class="summary-label">月初电量(度)</div></div>
         <div class="summary-item"><div class="summary-value" id="sEndSurplus">--</div><div class="summary-label">月末电量(度)</div></div>
       </div>
@@ -60,6 +62,7 @@
             <th>日期</th>
             <th>剩余电量(度)</th>
             <th>日耗电(度)</th>
+            <th>充值电量(度)</th>
             <th>记录方式</th>
           </tr>
         </thead>